From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: akpm@linux-foundation.org, gregkh@linuxfoundation.org,
rafael@kernel.org, viro@zeniv.linux.org.uk,
darrick.wong@oracle.com, paulmck@linux.vnet.ibm.com,
josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
hughd@google.com, shuah@kernel.org, robh@kernel.org,
ulf.hansson@linaro.org, aspriel@gmail.com,
vivek.gautam@codeaurora.org, robin.murphy@arm.com,
joe@perches.com, heikki.krogerus@linux.intel.com,
ktkhai@virtuozzo.com, sfr@canb.auug.org.au,
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chris@chris-wilson.co.uk, penguin-kernel@I-love.SAKURA.ne.jp,
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mingo@kernel.org, mhiramat@kernel.org,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH RFC 00/10] Introduce lockless shrink_slab()
Date: Tue, 07 Aug 2018 18:37:19 +0300 [thread overview]
Message-ID: <153365347929.19074.12509495712735843805.stgit@localhost.localdomain> (raw)
After bitmaps of not-empty memcg shrinkers were implemented
(see "[PATCH v9 00/17] Improve shrink_slab() scalability..."
series, which is already in mm tree), all the evil in perf
trace has moved from shrink_slab() to down_read_trylock().
As reported by Shakeel Butt:
> I created 255 memcgs, 255 ext4 mounts and made each memcg create a
> file containing few KiBs on corresponding mount. Then in a separate
> memcg of 200 MiB limit ran a fork-bomb.
>
> I ran the "perf record -ag -- sleep 60" and below are the results:
> + 47.49% fb.sh [kernel.kallsyms] [k] down_read_trylock
> + 30.72% fb.sh [kernel.kallsyms] [k] up_read
> + 9.51% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter
> + 1.69% fb.sh [kernel.kallsyms] [k] shrink_node_memcg
> + 1.35% fb.sh [kernel.kallsyms] [k] mem_cgroup_protected
> + 1.05% fb.sh [kernel.kallsyms] [k] queued_spin_lock_slowpath
> + 0.85% fb.sh [kernel.kallsyms] [k] _raw_spin_lock
> + 0.78% fb.sh [kernel.kallsyms] [k] lruvec_lru_size
> + 0.57% fb.sh [kernel.kallsyms] [k] shrink_node
> + 0.54% fb.sh [kernel.kallsyms] [k] queue_work_on
> + 0.46% fb.sh [kernel.kallsyms] [k] shrink_slab_memcg
The patchset continues to improve shrink_slab() scalability and makes
it lockless completely. Here are several steps for that:
1)Use SRCU to synchronize shrink_slab() and unregister_shrinker().
Nothing exiting is here, just srcu_read_lock() in shrink_slab()
and shrink_slab_memcg() and synchronize_srcu() in unregister_shrinker().
See [2/10] for details.
2)The above requires to make SRCU unconditional enabled.
[1/10] makes this. Note, that if we can't always enable
SRCU, we may use percpu_rw_semaphore instead of this.
See comment to [2/10] for details.
3)Convert shrinker_rwsem to mutex. Just cleanup.
4)Further patches make possible to speed up unregister_shrinker()
by splitting it in two stages. The first stage unlinks shrinker
from shrinker_list and shrinker_idr, while the second finalizes
the thing by calling synchronize_srcu() and freeing memory.
Patch [4/10] actually splits unregister_shrinker(), while
[10/10] makes superblock shrinker to use the new helpers
(unregister_shrinker_delayed_{initiate,finalize}().
5)Patches [5-9/10] are preparations on fs, which make possible
to split superblock unregistration in two stages. They sequentially
make super_cache_count() and super_cache_scan() safe to be called
on unregistering shrinker:
[cpu0] [cpu1]
unregister_shrinker_delayed_initiate(shrinker)
... shrink_slab(shrinker) (OK!)
unregister_shrinker_delayed_finalize(shrinker)
After all of this, shrink_slab() becomes lockless, while unregister_shrinker()
remains fast at least for superblock shrinker (another shrinkers also
can be made to unregister in the same delayed manner).
(This requires "mm: Use special value SHRINKER_REGISTERING instead list_empty() check"
from https://lkml.org/lkml/2018/8/6/276, which is on the way to -mm tree, as said
by -mm tree notification message from Andrew).
---
Kirill Tkhai (10):
rcu: Make CONFIG_SRCU unconditionally enabled
mm: Make shrink_slab() lockless
mm: Convert shrinker_rwsem to mutex
mm: Split unregister_shrinker()
fs: Move list_lru_destroy() to destroy_super_work()
fs: Shrink only (SB_ACTIVE|SB_BORN) superblocks in super_cache_scan()
fs: Introduce struct super_operations::destroy_super() callback.
xfs: Introduce xfs_fs_destroy_super()
shmem: Implement shmem_destroy_super()
fs: Use unregister_shrinker_delayed_{initiate,finalize} for super_block shrinker
drivers/base/core.c | 42 ----------
fs/super.c | 32 ++++----
fs/xfs/xfs_super.c | 14 +++
include/linux/device.h | 2
include/linux/fs.h | 6 +
include/linux/rcutiny.h | 4 -
include/linux/shrinker.h | 2
include/linux/srcu.h | 5 -
kernel/notifier.c | 3 -
kernel/rcu/Kconfig | 12 ---
kernel/rcu/tree.h | 5 -
kernel/rcu/update.c | 4 -
mm/shmem.c | 8 ++
mm/vmscan.c | 82 ++++++++++----------
.../selftests/rcutorture/doc/TREE_RCU-kconfig.txt | 5 -
15 files changed, 89 insertions(+), 137 deletions(-)
--
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
next reply other threads:[~2018-08-07 15:37 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-07 15:37 Kirill Tkhai [this message]
2018-08-07 15:37 ` [PATCH RFC 01/10] rcu: Make CONFIG_SRCU unconditionally enabled Kirill Tkhai
2018-08-08 0:55 ` Steven Rostedt
2018-08-08 1:05 ` Stephen Rothwell
2018-08-08 9:46 ` Kirill Tkhai
2018-08-08 1:08 ` Stephen Rothwell
2018-08-08 9:59 ` Kirill Tkhai
2018-08-08 11:04 ` Stephen Rothwell
2018-08-08 7:20 ` Michal Hocko
2018-08-08 10:17 ` Kirill Tkhai
2018-08-08 10:27 ` Michal Hocko
2018-08-08 21:31 ` Dave Chinner
2018-08-09 0:07 ` Matthew Wilcox
2018-08-09 7:45 ` Greg KH
2018-08-09 10:22 ` Kirill Tkhai
2018-08-08 16:13 ` Josh Triplett
2018-08-08 16:23 ` Kirill Tkhai
2018-08-08 16:30 ` Kirill Tkhai
2018-08-08 18:01 ` Josh Triplett
2018-08-08 23:02 ` Shakeel Butt
2018-08-08 23:09 ` Josh Triplett
2018-08-07 15:37 ` [PATCH RFC 02/10] mm: Make shrink_slab() lockless Kirill Tkhai
2018-08-08 11:51 ` Kirill Tkhai
2018-08-08 13:20 ` [PATCH RFC v2 " Kirill Tkhai
2018-08-09 7:14 ` Michal Hocko
2018-08-09 9:21 ` Kirill Tkhai
2018-08-09 10:37 ` Tetsuo Handa
2018-08-09 10:58 ` Kirill Tkhai
2018-08-09 11:23 ` Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 03/10] mm: Convert shrinker_rwsem to mutex Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 04/10] mm: Split unregister_shrinker() Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 05/10] fs: Move list_lru_destroy() to destroy_super_work() Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 06/10] fs: Shrink only (SB_ACTIVE|SB_BORN) superblocks in super_cache_scan() Kirill Tkhai
2018-08-07 15:38 ` [PATCH RFC 07/10] fs: Introduce struct super_operations::destroy_super() callback Kirill Tkhai
2018-08-07 15:39 ` [PATCH RFC 08/10] xfs: Introduce xfs_fs_destroy_super() Kirill Tkhai
2018-08-07 15:39 ` [PATCH RFC 09/10] shmem: Implement shmem_destroy_super() Kirill Tkhai
2018-08-07 15:39 ` [PATCH RFC 10/10] fs: Use unregister_shrinker_delayed_{initiate, finalize} for super_block shrinker Kirill Tkhai
2018-08-08 1:12 ` [PATCH RFC 00/10] Introduce lockless shrink_slab() Stephen Rothwell
2018-08-08 5:39 ` Shakeel Butt
2018-08-08 10:18 ` Kirill Tkhai
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