blkiocg_file_write_u64() has single switch case. Drop
blkiocg_file_write_u64(), rename blkio_weight_write() to
blkcg_set_weight() and use it directly for .write_u64 callback.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkcg stats handling is a mess. None of the stats has much to do with
blkcg core but they are all implemented in blkcg core. Code sharing
is achieved by mixing common code with hard-coded cases for each stat
counter.
This patch restructures statistics printing such that
* Common logic exists as helper functions and specific print functions
use the helpers to implement specific cases.
* Printing functions serving multiple counters don't require hardcoded
switching on specific counters.
* Printing uses read_seq_string callback (other methods will be phased
out).
This change enables further cleanups and relocating stats code to the
policy implementation it belongs to.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values
on 32bit archs and some stat counters have subtypes to distinguish
read/writes and sync/async IOs. The stat code paths are confusing and
involve a lot of going back and forth between blkcg core and specific
policy implementations, and synchronization and subtype handling are
open coded in blkcg core.
This patch introduces struct blkg_stat and blkg_rwstat which, with
accompanying operations, encapsulate stat updating and accessing with
proper synchronization.
blkg_stat is simple u64 counter with 64bit read-access protection.
blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw
flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and
replaces stat_sub_type indexed arrays.
All counters in blkio_group_stats and blkio_group_stats_cpu are
replaced with either blkg_stat or blkg_rwstat along with all users.
This does add one u64_stats_sync per counter and increase stats_sync
operations but they're empty/noops on 64bit archs and blkcg doesn't
have too many counters, especially with DEBUG_BLK_CGROUP off.
While the currently resulting code isn't necessarily simpler at the
moment, this will enable further clean up of blkcg stats code.
- BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to
BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}.
- blkg_stat_add() replaces blkio_add_stat() and
blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the
latter function no longer exists. It's *way* better to have
underflowed stat counters than oopsing.
- blkio_group_stats->dequeue is now a proper u64 stat counter instead
of ulong.
- reset_stats() updated to clear each stat counters individually and
BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed.
- Some functions reconstruct rw flags from direction and sync
booleans. This will be removed by future patches.
Signed-off-by: Tejun Heo <tj@kernel.org>
BLKIO_STAT_CPU_SECTORS doesn't need read/write/sync/async subcounters
and is counted by blkio_group_stats_cpu->sectors; however, it still
holds a member in blkio_group_stats_cpu->stat_arr_cpu.
Rearrange stat_type_cpu and define BLKIO_STAT_CPU_ARR_NR and use it
for stat_arr_cpu[] size so that only SERVICE_BYTES and SERVICED have
subcounters.
Signed-off-by: Tejun Heo <tj@kernel.org>
In cfq, when we calculate a time slice for a process(or a cfqq to
be precise), we have to consider the cfq_target_latency so that all the
sync request have an estimated latency(300ms) and it is controlled by
cfq_target_latency. But in some hadoop test, we have found that if
there are many processes doing sequential read(24 for example), the
throughput is bad because every process can only work for about 25ms
and the cfqq is switched. That leads to a higher disk seek. We can
achive the good throughput by setting low_latency=0, but then some
read's latency is too much for the application.
So this patch makes cfq_target_latency tunable through sysfs so that
we can tune it and find some magic number which is not bad for both
the throughput and the read latency.
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
cgroup/for-3.5 contains the following changes which blk-cgroup needs
to proceed with the on-going cleanup.
* Dynamic addition and removal of cftypes to make config/stat file
handling modular for policies.
* cgroup removal update to not wait for css references to drain to fix
blkcg removal hang caused by cfq caching cfqgs.
Pull in cgroup/for-3.5 into block/for-3.5/core. This causes the
following conflicts in block/blk-cgroup.c.
* 761b3ef50e "cgroup: remove cgroup_subsys argument from callbacks"
conflicts with blkiocg_pre_destroy() addition and blkiocg_attach()
removal. Resolved by removing @subsys from all subsys methods.
* 676f7c8f84 "cgroup: relocate cftype and cgroup_subsys definitions in
controllers" conflicts with ->pre_destroy() and ->attach() updates
and removal of modular config. Resolved by dropping forward
declarations of the methods and applying updates to the relocated
blkio_subsys.
* 4baf6e3325 "cgroup: convert all non-memcg controllers to the new
cftype interface" builds upon the previous item. Resolved by adding
->base_cftypes to the relocated blkio_subsys.
Signed-off-by: Tejun Heo <tj@kernel.org>
Convert debug, freezer, cpuset, cpu_cgroup, cpuacct, net_prio, blkio,
net_cls and device controllers to use the new cftype based interface.
Termination entry is added to cftype arrays and populate callbacks are
replaced with cgroup_subsys->base_cftypes initializations.
This is functionally identical transformation. There shouldn't be any
visible behavior change.
memcg is rather special and will be converted separately.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Vivek Goyal <vgoyal@redhat.com>
blk-cgroup, netprio_cgroup, cls_cgroup and tcp_memcontrol
unnecessarily define cftype array and cgroup_subsys structures at the
top of the file, which is unconventional and necessiates forward
declaration of methods.
This patch relocates those below the definitions of the methods and
removes the forward declarations. Note that forward declaration of
tcp_files[] is added in tcp_memcontrol.c for tcp_init_cgroup(). This
will be removed soon by another patch.
This patch doesn't introduce any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Smatch complains that we re-enable IRQs twice. It looks like we forgot
to disable them here on the spin_trylock() failure path. This was added
in 9f13ef678e "blkcg: use double locking instead of RCU for blkg
synchronization".
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>`
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We should use the GFP flags that the caller specified instead of picking
our own. All the callers specify GFP_KERNEL so this doesn't make a
difference to how the kernel runs, it's just a cleanup.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull cgroup changes from Tejun Heo:
"Out of the 8 commits, one fixes a long-standing locking issue around
tasklist walking and others are cleanups."
* 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list
cgroup: Remove wrong comment on cgroup_enable_task_cg_list()
cgroup: remove cgroup_subsys argument from callbacks
cgroup: remove extra calls to find_existing_css_set
cgroup: replace tasklist_lock with rcu_read_lock
cgroup: simplify double-check locking in cgroup_attach_proc
cgroup: move struct cgroup_pidlist out from the header file
cgroup: remove cgroup_attach_task_current_cg()
Pull scheduler changes for v3.4 from Ingo Molnar
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
printk: Make it compile with !CONFIG_PRINTK
sched/x86: Fix overflow in cyc2ns_offset
sched: Fix nohz load accounting -- again!
sched: Update yield() docs
printk/sched: Introduce special printk_sched() for those awkward moments
sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer
sched: Cleanup cpu_active madness
sched: Fix load-balance wreckage
sched: Clean up parameter passing of proc_sched_autogroup_set_nice()
sched: Ditch per cgroup task lists for load-balancing
sched: Rename load-balancing fields
sched: Move load-balancing arguments into helper struct
sched/rt: Do not submit new work when PI-blocked
sched/rt: Prevent idle task boosting
sched/wait: Add __wake_up_all_locked() API
sched/rt: Document scheduler related skip-resched-check sites
sched/rt: Use schedule_preempt_disabled()
sched/rt: Add schedule_preempt_disabled()
sched/rt: Do not throttle when PI boosting
sched/rt: Keep period timer ticking when rt throttling is active
...
After the previous patch to cfq, there's no ioc_get_changed() user
left. This patch yanks out ioc_{ioprio|cgroup|get}_changed() and all
related stuff.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
cfq caches the associated cfqq's for a given cic. The cache needs to
be flushed if the cic's ioprio or blkcg has changed. It is currently
done by requiring the changing action to set the respective
ICQ_*_CHANGED bit in the icq and testing it from cfq_set_request(),
which involves iterating through all the affected icqs.
All cfq wants to know is whether ioprio and/or blkcg have changed
since the last flush and can be easily achieved by just remembering
the current ioprio and blkcg ID in cic.
This patch adds cic->{ioprio|blkcg_id}, updates all ioprio users to
use the remembered value instead, and updates cfq_set_request() path
such that, instead of using icq_get_changed(), the current values are
compared against the remembered ones and trigger appropriate flush
action if not. Condition tests are moved inside both _changed
functions which are now named check_ioprio_changed() and
check_blkcg_changed().
ioprio.h::task_ioprio*() can't be used anymore and replaced with
open-coded IOPRIO_CLASS_NONE case in cfq_async_queue_prio().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that io_cq is managed by block core and guaranteed to exist for
any in-flight request, it is easier and carries more information to
pass around cfq_io_cq than io_context.
This patch updates cfq_init_prio_data(), cfq_find_alloc_queue() and
cfq_get_queue() to take @cic instead of @ioc. This change removes a
duplicate cfq_cic_lookup() from cfq_find_alloc_queue().
This change enables the use of cic-cached ioprio in the next patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add 64bit unique id to blkcg. This will be used by policies which
want blkcg identity test to tell whether the associated blkcg has
changed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With recent plug merge updates, all non-percpu stat updates happen
under queue_lock making stats_lock unnecessary to synchronize stat
updates. The only synchronization necessary is stat reading, which
can be done using u64_stats_sync instead.
This patch removes blkio_group->stats_lock and adds
blkio_group_stats->syncp for reader synchronization.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Restructure blkio_get_stat() to prepare for removal of stats_lock.
* Define BLKIO_STAT_ARR_NR explicitly to denote which stats have
subtypes instead of using BLKIO_STAT_QUEUED.
* Separate out stat acquisition and printing. After this, there are
only two users of blkio_fill_stat(). Just open code it.
* The code was mixing MAX_KEY_LEN and MAX_KEY_LEN - 1. There's no
need to subtract one. Use MAX_KEY_LEN consistently.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blkiocg_reset_stats() implements stat reset for blkio.reset_stats
cgroupfs file. This feature is very unconventional and something
which shouldn't have been merged. It's only useful when there's only
one user or tool looking at the stats. As soon as multiple users
and/or tools are involved, it becomes useless as resetting disrupts
other usages. There are very good reasons why all other stats expect
readers to read values at the start and end of a period and subtract
to determine delta over the period.
The implementation is rather complex - some fields shouldn't be
cleared and it saves some fields, resets whole and restores for some
reason. Reset of percpu stats is also racy. The comment points to
64bit store atomicity for the reason but even without that stores for
zero can simply race with other CPUs doing RMW and get clobbered.
Simplify reset by
* Clear selectively instead of resetting and restoring.
* Grouping debug stat fields to be reset and using memset() over them.
* Not caring about stats_lock.
* Using memset() to reset percpu stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With recent plug merge updates, merged stats are no longer called for
plug merges and now only updated while holding queue_lock. As
stats_lock is scheduled to be removed, there's no reason to use percpu
for merged stats. Don't use percpu for merged stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Current per cpu stat allocation assumes GFP_KERNEL allocation flag. But in
IO path there are times when we want GFP_NOIO semantics. As there is no
way to pass the allocation flags to alloc_percpu(), this patch delays the
allocation of stats using a worker thread.
v2-> tejun suggested following changes. Changed the patch accordingly.
- move alloc_node location in structure
- reduce the size of names of some of the fields
- Reduce the scope of locking of alloc_list_lock
- Simplified stat_alloc_fn() by allocating stats for all
policies in one go and then assigning these to a group.
v3 -> Andrew suggested to put some comments in the code. Also raised
concerns about trying to allocate infinitely in case of allocation
failure. I have changed the logic to sleep for 10ms before retrying.
That should take care of non-preemptible UP kernels.
v4 -> Tejun had more suggestions.
- drop list_for_each_entry_all()
- instead of msleep() use queue_delayed_work()
- Some cleanups realted to more compact coding.
v5-> tejun suggested more cleanups leading to more compact code.
tj: - Relocated pcpu_stats into blkio_stat_alloc_fn().
- Minor comment update.
- This also fixes suspicious RCU usage warning caused by invoking
cgroup_path() from blkg_alloc() without holding RCU read lock.
Now that blkg_alloc() doesn't require sleepable context, RCU
read lock from blkg_lookup_create() is maintained throughout
blkg_alloc().
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block fixes from Jens Axboe:
"Been sitting on this for a while, but lets get this out the door.
This fixes various important bugs for 3.3 final, along with a few more
trivial ones. Please pull!"
* 'for-linus' of git://git.kernel.dk/linux-block:
block: fix ioc leak in put_io_context
block, sx8: fix pointer math issue getting fw version
Block: use a freezable workqueue for disk-event polling
drivers/block/DAC960: fix -Wuninitialized warning
drivers/block/DAC960: fix DAC960_V2_IOCTL_Opcode_T -Wenum-compare warning
block: fix __blkdev_get and add_disk race condition
block: Fix setting bio flags in drivers (sd_dif/floppy)
block: Fix NULL pointer dereference in sd_revalidate_disk
block: exit_io_context() should call elevator_exit_icq_fn()
block: simplify ioc_release_fn()
block: replace icq->changed with icq->flags
Tejun Heo
Tao Ma
Andi Kleen
Dan Carpenter
Linus Torvalds
Vivek Goyal