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329 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Johannes Weiner
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b910718a94 |
mm: vmscan: detect file thrashing at the reclaim root
We use refault information to determine whether the cache workingset is stable or transitioning, and dynamically adjust the inactive:active file LRU ratio so as to maximize protection from one-off cache during stable periods, and minimize IO during transitions. With cgroups and their nested LRU lists, we currently don't do this correctly. While recursive cgroup reclaim establishes a relative LRU order among the pages of all involved cgroups, refaults only affect the local LRU order in the cgroup in which they are occuring. As a result, cache transitions can take longer in a cgrouped system as the active pages of sibling cgroups aren't challenged when they should be. [ Right now, this is somewhat theoretical, because the siblings, under continued regular reclaim pressure, should eventually run out of inactive pages - and since inactive:active *size* balancing is also done on a cgroup-local level, we will challenge the active pages eventually in most cases. But the next patch will move that relative size enforcement to the reclaim root as well, and then this patch here will be necessary to propagate refault pressure to siblings. ] This patch moves refault detection to the root of reclaim. Instead of remembering the cgroup owner of an evicted page, remember the cgroup that caused the reclaim to happen. When refaults later occur, they'll correctly influence the cross-cgroup LRU order that reclaim follows. I.e. if global reclaim kicked out pages in some subgroup A/B/C, the refault of those pages will challenge the global LRU order, and not just the local order down inside C. [hannes@cmpxchg.org: use page_memcg() instead of another lookup] Link: http://lkml.kernel.org/r/20191115160722.GA309754@cmpxchg.org Link: http://lkml.kernel.org/r/20191107205334.158354-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
|
1b05117df7 |
mm: vmscan: harmonize writeback congestion tracking for nodes & memcgs
The current writeback congestion tracking has separate flags for kswapd reclaim (node level) and cgroup limit reclaim (memcg-node level). This is unnecessarily complicated: the lruvec is an existing abstraction layer for that node-memcg intersection. Introduce lruvec->flags and LRUVEC_CONGESTED. Then track that at the reclaim root level, which is either the NUMA node for global reclaim, or the cgroup-node intersection for cgroup reclaim. Link: http://lkml.kernel.org/r/20191022144803.302233-9-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
|
867e5e1de1 |
mm: clean up and clarify lruvec lookup procedure
There is a per-memcg lruvec and a NUMA node lruvec. Which one is being used is somewhat confusing right now, and it's easy to make mistakes - especially when it comes to global reclaim. How it works: when memory cgroups are enabled, we always use the root_mem_cgroup's per-node lruvecs. When memory cgroups are not compiled in or disabled at runtime, we use pgdat->lruvec. Document that in a comment. Due to the way the reclaim code is generalized, all lookups use the mem_cgroup_lruvec() helper function, and nobody should have to find the right lruvec manually right now. But to avoid future mistakes, rename the pgdat->lruvec member to pgdat->__lruvec and delete the convenience wrapper that suggests it's a commonly accessed member. While in this area, swap the mem_cgroup_lruvec() argument order. The name suggests a memcg operation, yet it takes a pgdat first and a memcg second. I have to double take every time I call this. Fix that. Link: http://lkml.kernel.org/r/20191022144803.302233-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Shakeel Butt
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fa40d1ee9f |
mm: vmscan: memcontrol: remove mem_cgroup_select_victim_node()
Since commit |
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Hao Lee
|
242c37b459 |
include/linux/memcontrol.h: fix comments based on per-node memcg
These comments should be updated as memcg limit enforcement has been moved from zones to nodes. Link: http://lkml.kernel.org/r/20191022150618.GA15519@haolee.github.io Signed-off-by: Hao Lee <haolee.swjtu@gmail.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Yafang Shao
|
9da83f3fc7 |
mm, memcg: clean up reclaim iter array
The mem_cgroup_reclaim_cookie is only used in memcg softlimit reclaim now, and the priority of the reclaim is always 0. We don't need to define the iter in struct mem_cgroup_per_node as an array any more. That could make the code more clear and save some space. Link: http://lkml.kernel.org/r/1569897728-1686-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Chris Down
|
1bc63fb127 |
mm, memcg: make scan aggression always exclude protection
This patch is an incremental improvement on the existing
memory.{low,min} relative reclaim work to base its scan pressure
calculations on how much protection is available compared to the current
usage, rather than how much the current usage is over some protection
threshold.
This change doesn't change the experience for the user in the normal
case too much. One benefit is that it replaces the (somewhat arbitrary)
100% cutoff with an indefinite slope, which makes it easier to ballpark
a memory.low value.
As well as this, the old methodology doesn't quite apply generically to
machines with varying amounts of physical memory. Let's say we have a
top level cgroup, workload.slice, and another top level cgroup,
system-management.slice. We want to roughly give 12G to
system-management.slice, so on a 32GB machine we set memory.low to 20GB
in workload.slice, and on a 64GB machine we set memory.low to 52GB.
However, because these are relative amounts to the total machine size,
while the amount of memory we want to generally be willing to yield to
system.slice is absolute (12G), we end up putting more pressure on
system.slice just because we have a larger machine and a larger workload
to fill it, which seems fairly unintuitive. With this new behaviour, we
don't end up with this unintended side effect.
Previously the way that memory.low protection works is that if you are
50% over a certain baseline, you get 50% of your normal scan pressure.
This is certainly better than the previous cliff-edge behaviour, but it
can be improved even further by always considering memory under the
currently enforced protection threshold to be out of bounds. This means
that we can set relatively low memory.low thresholds for variable or
bursty workloads while still getting a reasonable level of protection,
whereas with the previous version we may still trivially hit the 100%
clamp. The previous 100% clamp is also somewhat arbitrary, whereas this
one is more concretely based on the currently enforced protection
threshold, which is likely easier to reason about.
There is also a subtle issue with the way that proportional reclaim
worked previously -- it promotes having no memory.low, since it makes
pressure higher during low reclaim. This happens because we base our
scan pressure modulation on how far memory.current is between memory.min
and memory.low, but if memory.low is unset, we only use the overage
method. In most cromulent configurations, this then means that we end
up with *more* pressure than with no memory.low at all when we're in low
reclaim, which is not really very usable or expected.
With this patch, memory.low and memory.min affect reclaim pressure in a
more understandable and composable way. For example, from a user
standpoint, "protected" memory now remains untouchable from a reclaim
aggression standpoint, and users can also have more confidence that
bursty workloads will still receive some amount of guaranteed
protection.
Link: http://lkml.kernel.org/r/20190322160307.GA3316@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Chris Down
|
9de7ca46ad |
mm, memcg: make memory.emin the baseline for utilisation determination
Roman points out that when when we do the low reclaim pass, we scale the reclaim pressure relative to position between 0 and the maximum protection threshold. However, if the maximum protection is based on memory.elow, and memory.emin is above zero, this means we still may get binary behaviour on second-pass low reclaim. This is because we scale starting at 0, not starting at memory.emin, and since we don't scan at all below emin, we end up with cliff behaviour. This should be a fairly uncommon case since usually we don't go into the second pass, but it makes sense to scale our low reclaim pressure starting at emin. You can test this by catting two large sparse files, one in a cgroup with emin set to some moderate size compared to physical RAM, and another cgroup without any emin. In both cgroups, set an elow larger than 50% of physical RAM. The one with emin will have less page scanning, as reclaim pressure is lower. Rebase on top of and apply the same idea as what was applied to handle cgroup_memory=disable properly for the original proportional patch http://lkml.kernel.org/r/20190201045711.GA18302@chrisdown.name ("mm, memcg: Handle cgroup_disable=memory when getting memcg protection"). Link: http://lkml.kernel.org/r/20190201051810.GA18895@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Suggested-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Chris Down
|
9783aa9917 |
mm, memcg: proportional memory.{low,min} reclaim
cgroup v2 introduces two memory protection thresholds: memory.low (best-effort) and memory.min (hard protection). While they generally do what they say on the tin, there is a limitation in their implementation that makes them difficult to use effectively: that cliff behaviour often manifests when they become eligible for reclaim. This patch implements more intuitive and usable behaviour, where we gradually mount more reclaim pressure as cgroups further and further exceed their protection thresholds. This cliff edge behaviour happens because we only choose whether or not to reclaim based on whether the memcg is within its protection limits (see the use of mem_cgroup_protected in shrink_node), but we don't vary our reclaim behaviour based on this information. Imagine the following timeline, with the numbers the lruvec size in this zone: 1. memory.low=1000000, memory.current=999999. 0 pages may be scanned. 2. memory.low=1000000, memory.current=1000000. 0 pages may be scanned. 3. memory.low=1000000, memory.current=1000001. 1000001* pages may be scanned. (?!) * Of course, we won't usually scan all available pages in the zone even without this patch because of scan control priority, over-reclaim protection, etc. However, as shown by the tests at the end, these techniques don't sufficiently throttle such an extreme change in input, so cliff-like behaviour isn't really averted by their existence alone. Here's an example of how this plays out in practice. At Facebook, we are trying to protect various workloads from "system" software, like configuration management tools, metric collectors, etc (see this[0] case study). In order to find a suitable memory.low value, we start by determining the expected memory range within which the workload will be comfortable operating. This isn't an exact science -- memory usage deemed "comfortable" will vary over time due to user behaviour, differences in composition of work, etc, etc. As such we need to ballpark memory.low, but doing this is currently problematic: 1. If we end up setting it too low for the workload, it won't have *any* effect (see discussion above). The group will receive the full weight of reclaim and won't have any priority while competing with the less important system software, as if we had no memory.low configured at all. 2. Because of this behaviour, we end up erring on the side of setting it too high, such that the comfort range is reliably covered. However, protected memory is completely unavailable to the rest of the system, so we might cause undue memory and IO pressure there when we *know* we have some elasticity in the workload. 3. Even if we get the value totally right, smack in the middle of the comfort zone, we get extreme jumps between no pressure and full pressure that cause unpredictable pressure spikes in the workload due to the current binary reclaim behaviour. With this patch, we can set it to our ballpark estimation without too much worry. Any undesirable behaviour, such as too much or too little reclaim pressure on the workload or system will be proportional to how far our estimation is off. This means we can set memory.low much more conservatively and thus waste less resources *without* the risk of the workload falling off a cliff if we overshoot. As a more abstract technical description, this unintuitive behaviour results in having to give high-priority workloads a large protection buffer on top of their expected usage to function reliably, as otherwise we have abrupt periods of dramatically increased memory pressure which hamper performance. Having to set these thresholds so high wastes resources and generally works against the principle of work conservation. In addition, having proportional memory reclaim behaviour has other benefits. Most notably, before this patch it's basically mandatory to set memory.low to a higher than desirable value because otherwise as soon as you exceed memory.low, all protection is lost, and all pages are eligible to scan again. By contrast, having a gradual ramp in reclaim pressure means that you now still get some protection when thresholds are exceeded, which means that one can now be more comfortable setting memory.low to lower values without worrying that all protection will be lost. This is important because workingset size is really hard to know exactly, especially with variable workloads, so at least getting *some* protection if your workingset size grows larger than you expect increases user confidence in setting memory.low without a huge buffer on top being needed. Thanks a lot to Johannes Weiner and Tejun Heo for their advice and assistance in thinking about how to make this work better. In testing these changes, I intended to verify that: 1. Changes in page scanning become gradual and proportional instead of binary. To test this, I experimented stepping further and further down memory.low protection on a workload that floats around 19G workingset when under memory.low protection, watching page scan rates for the workload cgroup: +------------+-----------------+--------------------+--------------+ | memory.low | test (pgscan/s) | control (pgscan/s) | % of control | +------------+-----------------+--------------------+--------------+ | 21G | 0 | 0 | N/A | | 17G | 867 | 3799 | 23% | | 12G | 1203 | 3543 | 34% | | 8G | 2534 | 3979 | 64% | | 4G | 3980 | 4147 | 96% | | 0 | 3799 | 3980 | 95% | +------------+-----------------+--------------------+--------------+ As you can see, the test kernel (with a kernel containing this patch) ramps up page scanning significantly more gradually than the control kernel (without this patch). 2. More gradual ramp up in reclaim aggression doesn't result in premature OOMs. To test this, I wrote a script that slowly increments the number of pages held by stress(1)'s --vm-keep mode until a production system entered severe overall memory contention. This script runs in a highly protected slice taking up the majority of available system memory. Watching vmstat revealed that page scanning continued essentially nominally between test and control, without causing forward reclaim progress to become arrested. [0]: https://facebookmicrosites.github.io/cgroup2/docs/overview.html#case-study-the-fbtax2-project [akpm@linux-foundation.org: reflow block comments to fit in 80 cols] [chris@chrisdown.name: handle cgroup_disable=memory when getting memcg protection] Link: http://lkml.kernel.org/r/20190201045711.GA18302@chrisdown.name Link: http://lkml.kernel.org/r/20190124014455.GA6396@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Baoquan He
|
08d1d0e6d0 |
memcg: only record foreign writebacks with dirty pages when memcg is not disabled
In kdump kernel, memcg usually is disabled with 'cgroup_disable=memory' for saving memory. Now kdump kernel will always panic when dump vmcore to local disk: BUG: kernel NULL pointer dereference, address: 0000000000000ab8 Oops: 0000 [#1] SMP NOPTI CPU: 0 PID: 598 Comm: makedumpfile Not tainted 5.3.0+ #26 Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 10/02/2018 RIP: 0010:mem_cgroup_track_foreign_dirty_slowpath+0x38/0x140 Call Trace: __set_page_dirty+0x52/0xc0 iomap_set_page_dirty+0x50/0x90 iomap_write_end+0x6e/0x270 iomap_write_actor+0xce/0x170 iomap_apply+0xba/0x11e iomap_file_buffered_write+0x62/0x90 xfs_file_buffered_aio_write+0xca/0x320 [xfs] new_sync_write+0x12d/0x1d0 vfs_write+0xa5/0x1a0 ksys_write+0x59/0xd0 do_syscall_64+0x59/0x1e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 And this will corrupt the 1st kernel too with 'cgroup_disable=memory'. Via the trace and with debugging, it is pointing to commit |
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Yang Shi
|
87eaceb3fa |
mm: thp: make deferred split shrinker memcg aware
Currently THP deferred split shrinker is not memcg aware, this may cause premature OOM with some configuration. For example the below test would run into premature OOM easily: $ cgcreate -g memory:thp $ echo 4G > /sys/fs/cgroup/memory/thp/memory/limit_in_bytes $ cgexec -g memory:thp transhuge-stress 4000 transhuge-stress comes from kernel selftest. It is easy to hit OOM, but there are still a lot THP on the deferred split queue, memcg direct reclaim can't touch them since the deferred split shrinker is not memcg aware. Convert deferred split shrinker memcg aware by introducing per memcg deferred split queue. The THP should be on either per node or per memcg deferred split queue if it belongs to a memcg. When the page is immigrated to the other memcg, it will be immigrated to the target memcg's deferred split queue too. Reuse the second tail page's deferred_list for per memcg list since the same THP can't be on multiple deferred split queues. [yang.shi@linux.alibaba.com: simplify deferred split queue dereference per Kirill Tkhai] Link: http://lkml.kernel.org/r/1566496227-84952-5-git-send-email-yang.shi@linux.alibaba.com Link: http://lkml.kernel.org/r/1565144277-36240-5-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Yang Shi
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0a432dcbeb |
mm: shrinker: make shrinker not depend on memcg kmem
Currently shrinker is just allocated and can work when memcg kmem is enabled. But, THP deferred split shrinker is not slab shrinker, it doesn't make too much sense to have such shrinker depend on memcg kmem. It should be able to reclaim THP even though memcg kmem is disabled. Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker. When memcg kmem is disabled, just such shrinkers can be called in shrinking memcg slab. [yang.shi@linux.alibaba.com: add comment] Link: http://lkml.kernel.org/r/1566496227-84952-4-git-send-email-yang.shi@linux.alibaba.com Link: http://lkml.kernel.org/r/1565144277-36240-4-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
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7ad67ca553 |
Merge tag 'for-5.4/block-2019-09-16' of git://git.kernel.dk/linux-block
Pull block updates from Jens Axboe:
- Two NVMe pull requests:
- ana log parse fix from Anton
- nvme quirks support for Apple devices from Ben
- fix missing bio completion tracing for multipath stack devices
from Hannes and Mikhail
- IP TOS settings for nvme rdma and tcp transports from Israel
- rq_dma_dir cleanups from Israel
- tracing for Get LBA Status command from Minwoo
- Some nvme-tcp cleanups from Minwoo, Potnuri and Myself
- Some consolidation between the fabrics transports for handling
the CAP register
- reset race with ns scanning fix for fabrics (move fabrics
commands to a dedicated request queue with a different lifetime
from the admin request queue)."
- controller reset and namespace scan races fixes
- nvme discovery log change uevent support
- naming improvements from Keith
- multiple discovery controllers reject fix from James
- some regular cleanups from various people
- Series fixing (and re-fixing) null_blk debug printing and nr_devices
checks (André)
- A few pull requests from Song, with fixes from Andy, Guoqing,
Guilherme, Neil, Nigel, and Yufen.
- REQ_OP_ZONE_RESET_ALL support (Chaitanya)
- Bio merge handling unification (Christoph)
- Pick default elevator correctly for devices with special needs
(Damien)
- Block stats fixes (Hou)
- Timeout and support devices nbd fixes (Mike)
- Series fixing races around elevator switching and device add/remove
(Ming)
- sed-opal cleanups (Revanth)
- Per device weight support for BFQ (Fam)
- Support for blk-iocost, a new model that can properly account cost of
IO workloads. (Tejun)
- blk-cgroup writeback fixes (Tejun)
- paride queue init fixes (zhengbin)
- blk_set_runtime_active() cleanup (Stanley)
- Block segment mapping optimizations (Bart)
- lightnvm fixes (Hans/Minwoo/YueHaibing)
- Various little fixes and cleanups
* tag 'for-5.4/block-2019-09-16' of git://git.kernel.dk/linux-block: (186 commits)
null_blk: format pr_* logs with pr_fmt
null_blk: match the type of parameter nr_devices
null_blk: do not fail the module load with zero devices
block: also check RQF_STATS in blk_mq_need_time_stamp()
block: make rq sector size accessible for block stats
bfq: Fix bfq linkage error
raid5: use bio_end_sector in r5_next_bio
raid5: remove STRIPE_OPS_REQ_PENDING
md: add feature flag MD_FEATURE_RAID0_LAYOUT
md/raid0: avoid RAID0 data corruption due to layout confusion.
raid5: don't set STRIPE_HANDLE to stripe which is in batch list
raid5: don't increment read_errors on EILSEQ return
nvmet: fix a wrong error status returned in error log page
nvme: send discovery log page change events to userspace
nvme: add uevent variables for controller devices
nvme: enable aen regardless of the presence of I/O queues
nvme-fabrics: allow discovery subsystems accept a kato
nvmet: Use PTR_ERR_OR_ZERO() in nvmet_init_discovery()
nvme: Remove redundant assignment of cq vector
nvme: Assign subsys instance from first ctrl
...
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Tejun Heo
|
97b27821b4 |
writeback, memcg: Implement foreign dirty flushing
There's an inherent mismatch between memcg and writeback. The former
trackes ownership per-page while the latter per-inode. This was a
deliberate design decision because honoring per-page ownership in the
writeback path is complicated, may lead to higher CPU and IO overheads
and deemed unnecessary given that write-sharing an inode across
different cgroups isn't a common use-case.
Combined with inode majority-writer ownership switching, this works
well enough in most cases but there are some pathological cases. For
example, let's say there are two cgroups A and B which keep writing to
different but confined parts of the same inode. B owns the inode and
A's memory is limited far below B's. A's dirty ratio can rise enough
to trigger balance_dirty_pages() sleeps but B's can be low enough to
avoid triggering background writeback. A will be slowed down without
a way to make writeback of the dirty pages happen.
This patch implements foreign dirty recording and foreign mechanism so
that when a memcg encounters a condition as above it can trigger
flushes on bdi_writebacks which can clean its pages. Please see the
comment on top of mem_cgroup_track_foreign_dirty_slowpath() for
details.
A reproducer follows.
write-range.c::
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
static const char *usage = "write-range FILE START SIZE\n";
int main(int argc, char **argv)
{
int fd;
unsigned long start, size, end, pos;
char *endp;
char buf[4096];
if (argc < 4) {
fprintf(stderr, usage);
return 1;
}
fd = open(argv[1], O_WRONLY);
if (fd < 0) {
perror("open");
return 1;
}
start = strtoul(argv[2], &endp, 0);
if (*endp != '\0') {
fprintf(stderr, usage);
return 1;
}
size = strtoul(argv[3], &endp, 0);
if (*endp != '\0') {
fprintf(stderr, usage);
return 1;
}
end = start + size;
while (1) {
for (pos = start; pos < end; ) {
long bread, bwritten = 0;
if (lseek(fd, pos, SEEK_SET) < 0) {
perror("lseek");
return 1;
}
bread = read(0, buf, sizeof(buf) < end - pos ?
sizeof(buf) : end - pos);
if (bread < 0) {
perror("read");
return 1;
}
if (bread == 0)
return 0;
while (bwritten < bread) {
long this;
this = write(fd, buf + bwritten,
bread - bwritten);
if (this < 0) {
perror("write");
return 1;
}
bwritten += this;
pos += bwritten;
}
}
}
}
repro.sh::
#!/bin/bash
set -e
set -x
sysctl -w vm.dirty_expire_centisecs=300000
sysctl -w vm.dirty_writeback_centisecs=300000
sysctl -w vm.dirtytime_expire_seconds=300000
echo 3 > /proc/sys/vm/drop_caches
TEST=/sys/fs/cgroup/test
A=$TEST/A
B=$TEST/B
mkdir -p $A $B
echo "+memory +io" > $TEST/cgroup.subtree_control
echo $((1<<30)) > $A/memory.high
echo $((32<<30)) > $B/memory.high
rm -f testfile
touch testfile
fallocate -l 4G testfile
echo "Starting B"
(echo $BASHPID > $B/cgroup.procs
pv -q --rate-limit 70M < /dev/urandom | ./write-range testfile $((2<<30)) $((2<<30))) &
echo "Waiting 10s to ensure B claims the testfile inode"
sleep 5
sync
sleep 5
sync
echo "Starting A"
(echo $BASHPID > $A/cgroup.procs
pv < /dev/urandom | ./write-range testfile 0 $((2<<30)))
v2: Added comments explaining why the specific intervals are being used.
v3: Use 0 @nr when calling cgroup_writeback_by_id() to use best-effort
flushing while avoding possible livelocks.
v4: Use get_jiffies_64() and time_before/after64() instead of raw
jiffies_64 and arthimetic comparisons as suggested by Jan.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
||
Roman Gushchin
|
ec9f02384f |
mm: workingset: fix vmstat counters for shadow nodes
Memcg counters for shadow nodes are broken because the memcg pointer is
obtained in a wrong way. The following approach is used:
virt_to_page(xa_node)->mem_cgroup
Since commit
|
||
|
Shakeel Butt
|
6ba749ee78 |
mm, oom: remove redundant task_in_mem_cgroup() check
oom_unkillable_task() can be called from three different contexts i.e. global OOM, memcg OOM and oom_score procfs interface. At the moment oom_unkillable_task() does a task_in_mem_cgroup() check on the given process. Since there is no reason to perform task_in_mem_cgroup() check for global OOM and oom_score procfs interface, those contexts provide NULL memcg and skips the task_in_mem_cgroup() check. However for memcg OOM context, the oom_unkillable_task() is always called from mem_cgroup_scan_tasks() and thus task_in_mem_cgroup() check becomes redundant and effectively dead code. So, just remove the task_in_mem_cgroup() check altogether. Link: http://lkml.kernel.org/r/20190624212631.87212-2-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Paul Jackson <pj@sgi.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Roman Gushchin
|
49a18eae2e |
mm: memcg/slab: introduce __memcg_kmem_uncharge_memcg()
Let's separate the page counter modification code out of __memcg_kmem_uncharge() in a way similar to what __memcg_kmem_charge() and __memcg_kmem_charge_memcg() work. This will allow to reuse this code later using a new memcg_kmem_uncharge_memcg() wrapper, which calls __memcg_kmem_uncharge_memcg() if memcg_kmem_enabled() check is passed. Link: http://lkml.kernel.org/r/20190611231813.3148843-5-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Waiman Long <longman@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Andrei Vagin <avagin@gmail.com> Cc: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Shakeel Butt
|
1e577f970f |
mm, memcg: introduce memory.events.local
The memory controller in cgroup v2 exposes memory.events file for each memcg which shows the number of times events like low, high, max, oom and oom_kill have happened for the whole tree rooted at that memcg. Users can also poll or register notification to monitor the changes in that file. Any event at any level of the tree rooted at memcg will notify all the listeners along the path till root_mem_cgroup. There are existing users which depend on this behavior. However there are users which are only interested in the events happening at a specific level of the memcg tree and not in the events in the underlying tree rooted at that memcg. One such use-case is a centralized resource monitor which can dynamically adjust the limits of the jobs running on a system. The jobs can create their sub-hierarchy for their own sub-tasks. The centralized monitor is only interested in the events at the top level memcgs of the jobs as it can then act and adjust the limits of the jobs. Using the current memory.events for such centralized monitor is very inconvenient. The monitor will keep receiving events which it is not interested and to find if the received event is interesting, it has to read memory.event files of the next level and compare it with the top level one. So, let's introduce memory.events.local to the memcg which shows and notify for the events at the memcg level. Now, does memory.stat and memory.pressure need their local versions. IMHO no due to the no internal process contraint of the cgroup v2. The memory.stat file of the top level memcg of a job shows the stats and vmevents of the whole tree. The local stats or vmevents of the top level memcg will only change if there is a process running in that memcg but v2 does not allow that. Similarly for memory.pressure there will not be any process in the internal nodes and thus no chance of local pressure. Link: http://lkml.kernel.org/r/20190527174643.209172-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Chris Down <chris@chrisdown.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
815744d751 |
mm: memcontrol: don't batch updates of local VM stats and events
The kernel test robot noticed a 26% will-it-scale pagefault regression from commit |
||
|
Chris Down
|
9852ae3fe5 |
mm, memcg: consider subtrees in memory.events
memory.stat and other files already consider subtrees in their output, and
we should too in order to not present an inconsistent interface.
The current situation is fairly confusing, because people interacting with
cgroups expect hierarchical behaviour in the vein of memory.stat,
cgroup.events, and other files. For example, this causes confusion when
debugging reclaim events under low, as currently these always read "0" at
non-leaf memcg nodes, which frequently causes people to misdiagnose breach
behaviour. The same confusion applies to other counters in this file when
debugging issues.
Aggregation is done at write time instead of at read-time since these
counters aren't hot (unlike memory.stat which is per-page, so it does it
at read time), and it makes sense to bundle this with the file
notifications.
After this patch, events are propagated up the hierarchy:
[root@ktst ~]# cat /sys/fs/cgroup/system.slice/memory.events
low 0
high 0
max 0
oom 0
oom_kill 0
[root@ktst ~]# systemd-run -p MemoryMax=1 true
Running as unit: run-r251162a189fb4562b9dabfdc9b0422f5.service
[root@ktst ~]# cat /sys/fs/cgroup/system.slice/memory.events
low 0
high 0
max 7
oom 1
oom_kill 1
As this is a change in behaviour, this can be reverted to the old
behaviour by mounting with the `memory_localevents' flag set. However, we
use the new behaviour by default as there's a lack of evidence that there
are any current users of memory.events that would find this change
undesirable.
akpm: this is a behaviour change, so Cc:stable. THis is so that
forthcoming distros which use cgroup v2 are more likely to pick up the
revised behaviour.
Link: http://lkml.kernel.org/r/20190208224419.GA24772@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Thomas Gleixner
|
c942fddf87 |
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
Based on 3 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version [author] [kishon] [vijay] [abraham] [i] [kishon]@[ti] [com] this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version [author] [graeme] [gregory] [gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i] [kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema] [hk] [hemahk]@[ti] [com] this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1105 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|
Johannes Weiner
|
42a3003535 |
mm: memcontrol: fix recursive statistics correctness & scalabilty
Right now, when somebody needs to know the recursive memory statistics and events of a cgroup subtree, they need to walk the entire subtree and sum up the counters manually. There are two issues with this: 1. When a cgroup gets deleted, its stats are lost. The state counters should all be 0 at that point, of course, but the events are not. When this happens, the event counters, which are supposed to be monotonic, can go backwards in the parent cgroups. 2. During regular operation, we always have a certain number of lazily freed cgroups sitting around that have been deleted, have no tasks, but have a few cache pages remaining. These groups' statistics do not change until we eventually hit memory pressure, but somebody watching, say, memory.stat on an ancestor has to iterate those every time. This patch addresses both issues by introducing recursive counters at each level that are propagated from the write side when stats change. Upward propagation happens when the per-cpu caches spill over into the local atomic counter. This is the same thing we do during charge and uncharge, except that the latter uses atomic RMWs, which are more expensive; stat changes happen at around the same rate. In a sparse file test (page faults and reclaim at maximum CPU speed) with 5 cgroup nesting levels, perf shows __mod_memcg_page state at ~1%. Link: http://lkml.kernel.org/r/20190412151507.2769-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
db9adbcbe7 |
mm: memcontrol: move stat/event counting functions out-of-line
These are getting too big to be inlined in every callsite. They were
stolen from vmstat.c, which already out-of-lines them, and they have
only been growing since. The callsites aren't that hot, either.
Move __mod_memcg_state()
__mod_lruvec_state() and
__count_memcg_events() out of line and add kerneldoc comments.
Link: http://lkml.kernel.org/r/20190412151507.2769-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Johannes Weiner
|
205b20cc5a |
mm: memcontrol: make cgroup stats and events query API explicitly local
Patch series "mm: memcontrol: memory.stat cost & correctness". The cgroup memory.stat file holds recursive statistics for the entire subtree. The current implementation does this tree walk on-demand whenever the file is read. This is giving us problems in production. 1. The cost of aggregating the statistics on-demand is high. A lot of system service cgroups are mostly idle and their stats don't change between reads, yet we always have to check them. There are also always some lazily-dying cgroups sitting around that are pinned by a handful of remaining page cache; the same applies to them. In an application that periodically monitors memory.stat in our fleet, we have seen the aggregation consume up to 5% CPU time. 2. When cgroups die and disappear from the cgroup tree, so do their accumulated vm events. The result is that the event counters at higher-level cgroups can go backwards and confuse some of our automation, let alone people looking at the graphs over time. To address both issues, this patch series changes the stat implementation to spill counts upwards when the counters change. The upward spilling is batched using the existing per-cpu cache. In a sparse file stress test with 5 level cgroup nesting, the additional cost of the flushing was negligible (a little under 1% of CPU at 100% CPU utilization, compared to the 5% of reading memory.stat during regular operation). This patch (of 4): memcg_page_state(), lruvec_page_state(), memcg_sum_events() are currently returning the state of the local memcg or lruvec, not the recursive state. In practice there is a demand for both versions, although the callers that want the recursive counts currently sum them up by hand. Per default, cgroups are considered recursive entities and generally we expect more users of the recursive counters, with the local counts being special cases. To reflect that in the name, add a _local suffix to the current implementations. The following patch will re-incarnate these functions with recursive semantics, but with an O(1) implementation. [hannes@cmpxchg.org: fix bisection hole] Link: http://lkml.kernel.org/r/20190417160347.GC23013@cmpxchg.org Link: http://lkml.kernel.org/r/20190412151507.2769-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Chris Down
|
871789d4af |
mm, memcg: rename ambiguously named memory.stat counters and functions
I spent literally an hour trying to work out why an earlier version of my memory.events aggregation code doesn't work properly, only to find out I was calling memcg->events instead of memcg->memory_events, which is fairly confusing. This naming seems in need of reworking, so make it harder to do the wrong thing by using vmevents instead of events, which makes it more clear that these are vm counters rather than memcg-specific counters. There are also a few other inconsistent names in both the percpu and aggregated structs, so these are all cleaned up to be more coherent and easy to understand. This commit contains code cleanup only: there are no logic changes. [akpm@linux-foundation.org: fix it for preceding changes] Link: http://lkml.kernel.org/r/20190208224319.GA23801@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |