Patch series "Reduce preallocations for maple tree", v3.
Initial work on preallocations showed no regression in performance during
testing, but recently some users (both on [1] and off [android] list) have
reported that preallocating the worst-case number of nodes has caused some
slow down. This patch set addresses the number of allocations in a few
ways.
During munmap() most munmap() operations will remove a single VMA, so
leverage the fact that the maple tree can place a single pointer at range
0 - 0 without allocating. This is done by changing the index of the VMAs
to be indexed by the count, starting at 0.
Re-introduce the entry argument to mas_preallocate() so that a more
intelligent guess of the node count can be made.
Implement the more intelligent guess of the node count, although there is
more work to be done.
During development of v2 of this patch set, I also noticed that the number
of nodes being allocated for a rebalance was beyond what could possibly be
needed. This is addressed in patch 0008.
This patch (of 15):
Add a way to test the speed of mas_for_each() to the testing code.
Link: https://lkml.kernel.org/r/20230724183157.3939892-1-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20230724183157.3939892-2-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
test_pages() tests the page allocator by calling alloc_pages() with
different orders up to order 10.
However, different architectures and platforms support different maximum
contiguous allocation sizes. The default maximum allocation order
(MAX_ORDER) is 10, but architectures can use CONFIG_ARCH_FORCE_MAX_ORDER
to override this. On platforms where this is less than 10, test_meminit()
will blow up with a WARN(). This is expected, so let's not do that.
Replace the hardcoded "10" with the MAX_ORDER macro so that we test
allocations up to the expected platform limit.
Link: https://lkml.kernel.org/r/20230714015238.47931-1-ajd@linux.ibm.com
Fixes: 5015a300a5 ("lib: introduce test_meminit module")
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Xiaoke Wang <xkernel.wang@foxmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When the new range can be completely covered by the original last range
without touching the boundaries on both sides, two new entries can be
appended to the end as a fast path. We update the original last pivot at
the end, and the newly appended two entries will not be accessed before
this, so it is also safe in RCU mode.
This is useful for sequential insertion, which is what we do in
dup_mmap(). Enabling BENCH_FORK in test_maple_tree and just running
bench_forking() gives the following time-consuming numbers:
before: after:
17,874.83 msec 15,738.38 msec
It shows about a 12% performance improvement for duplicating VMAs.
Link: https://lkml.kernel.org/r/20230628073657.75314-4-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The documentation of mt_next() claims that it starts the search at the
provided index. That's incorrect as it starts the search after the
provided index.
The documentation of mt_find() is slightly confusing. "Handles locking"
is not really helpful as it does not explain how the "locking" works.
Also the documentation of index talks about a range, while in reality the
index is updated on a succesful search to the index of the found entry
plus one.
Fix similar issues for mt_find_after() and mt_prev().
Reword the confusing "Note: Will not return the zero entry." comment on
mt_for_each() and document @__index correctly.
Link: https://lkml.kernel.org/r/87ttw2n556.ffs@tglx
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shanker Donthineni <sdonthineni@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull char driver and Documentation fixes from Greg KH:
"Here is a char driver fix and some documentation updates for 6.5-rc4
that contain the following changes:
- sram/genalloc bugfix for reported problem
- security-bugs.rst update based on recent discussions
- embargoed-hardware-issues minor cleanups and then partial revert
for the project/company lists
All of these have been in linux-next for a while with no reported
problems, and the documentation updates have all been reviewed by the
relevant developers"
* tag 'char-misc-6.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
misc/genalloc: Name subpools by of_node_full_name()
Documentation: embargoed-hardware-issues.rst: add AMD to the list
Documentation: embargoed-hardware-issues.rst: clean out empty and unused entries
Documentation: security-bugs.rst: clarify CVE handling
Documentation: security-bugs.rst: update preferences when dealing with the linux-distros group
A previous commit tried to come up with more generic subpool
names, but this isn't quite working: the node name was used
elsewhere to match pools to consumers which regressed the
nVidia Tegra 2/3 video decoder.
Revert back to an earlier approach using of_node_full_name()
instead of just the name to make sure the pool name is more
unique, and change both sites using this in the kernel.
It is not perfect since two SRAM nodes could have the same
subpool name but it makes the situation better than before.
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Fixes: 21e5a2d10c ("misc: sram: Generate unique names for subpools")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20230622074520.3058027-1-linus.walleij@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull block fixes from Jens Axboe:
- Fix for loop regressions (Mauricio)
- Fix a potential stall with batched wakeups in sbitmap (David)
- Fix for stall with recursive plug flushes (Ross)
- Skip accounting of empty requests for blk-iocost (Chengming)
- Remove a dead field in struct blk_mq_hw_ctx (Chengming)
* tag 'block-6.5-2023-07-21' of git://git.kernel.dk/linux:
loop: do not enforce max_loop hard limit by (new) default
loop: deprecate autoloading callback loop_probe()
sbitmap: fix batching wakeup
blk-iocost: skip empty flush bio in iocost
blk-mq: delete dead struct blk_mq_hw_ctx->queued field
blk-mq: Fix stall due to recursive flush plug
