From: Chinwen Chang <chinwen.chang@mediatek.com>
To: Matthias Brugger <matthias.bgg@gmail.com>,
Michel Lespinasse <walken@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
Davidlohr Bueso <dbueso@suse.de>,
Chinwen Chang <chinwen.chang@mediatek.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
Steven Price <steven.price@arm.com>,
Song Liu <songliubraving@fb.com>,
Jimmy Assarsson <jimmyassarsson@gmail.com>,
Huang Ying <ying.huang@intel.com>
Cc: <linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-mediatek@lists.infradead.org>,
<linux-fsdevel@vger.kernel.org>, <wsd_upstream@mediatek.com>
Subject: [PATCH 0/2] Try to release mmap_lock temporarily in smaps_rollup
Date: Tue, 11 Aug 2020 12:42:33 +0800 [thread overview]
Message-ID: <1597120955-16495-1-git-send-email-chinwen.chang@mediatek.com> (raw)
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(+)
next reply other threads:[~2020-08-11 4:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 4:42 Chinwen Chang [this message]
2020-08-11 4:42 ` [PATCH 1/2] mmap locking API: add mmap_lock_is_contended() Chinwen Chang
2020-08-11 4:42 ` [PATCH 2/2] mm: proc: smaps_rollup: do not stall write attempts on mmap_lock Chinwen Chang
2020-08-12 8:39 ` Steven Price
2020-08-12 9:26 ` Chinwen Chang
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