lkml.org 
[lkml]   [2020]   [Aug]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject[PATCH 0/2] Try to release mmap_lock temporarily in smaps_rollup
Date
Recently, we have observed some janky issues caused by unpleasantly long
contention on mmap_lock which is held by smaps_rollup when probing large
processes. To address the problem, we let smaps_rollup detect if anyone
wants to acquire mmap_lock for write attempts. If yes, just release the
lock temporarily to ease the contention.

smaps_rollup is a procfs interface which allows users to summarize the
process's memory usage without the overhead of seq_* calls. Android uses
it to sample the memory usage of various processes to balance its memory
pool sizes. If no one wants to take the lock for write requests, smaps_rollup
with this patch will behave like the original one.

Although there are on-going mmap_lock optimizations like range-based locks,
the lock applied to smaps_rollup would be the coarse one, which is hard to
avoid the occurrence of aforementioned issues. So the detection and temporary
release for write attempts on mmap_lock in smaps_rollup is still necessary.


Chinwen Chang (2):
mmap locking API: add mmap_lock_is_contended()
mm: proc: smaps_rollup: do not stall write attempts on mmap_lock

fs/proc/task_mmu.c | 21 +++++++++++++++++++++
include/linux/mmap_lock.h | 5 +++++
2 files changed, 26 insertions(+)
\
 
 \ /
  Last update: 2020-08-11 06:45    [W:1.109 / U:0.508 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site