From: Andrew Morton <akpm@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, John Dias <joaodias@google.com>,
Tim Murray <timmurray@google.com>,
Matthew Wilcox <willy@infradead.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [PATCH v2] mm: don't be stuck to rmap lock on reclaim path
Date: Mon, 9 May 2022 11:54:49 -0700 [thread overview]
Message-ID: <20220509115449.f48559dd40a5e5ec95b8ead8@linux-foundation.org> (raw)
In-Reply-To: <20220509154710.4132957-1-minchan@kernel.org>
On Mon, 9 May 2022 08:47:10 -0700 Minchan Kim <minchan@kernel.org> wrote:
> The rmap locks(i_mmap_rwsem and anon_vma->root->rwsem) could be
> contented under memory pressure if processes keep working on
> their vmas(e.g., fork, mmap, munmap). It makes reclaim path
> stuck. In our real workload traces, we see kswapd is waiting the
> lock for 300ms+(a sec as worst case) and it makes other processes
> entering direct reclaim, which were also stuck on the lock.
>
> This patch makes LRU aging path try_lock mode like shink_page_list
> so the reclaim context will keep working with next LRU pages
> without being stuck.
>
> Since this patch introduces a new "contended" field as out-param
> along with try_lock in-param in rmap_walk_control, it's not
> immutable any longer if the try_lock is set so remove const
> keywords on rmap related functions. Since rmap walking is already
> expensive operation, I doubt the const would help sizable benefit(
> And we didn't have it until 5.17).
Some quantitative testing results would be helpful. Demonstrate
the benefits of the patch?
next prev parent reply other threads:[~2022-05-09 18:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-09 15:47 [PATCH v2] mm: don't be stuck to rmap lock on reclaim path Minchan Kim
2022-05-09 18:54 ` Andrew Morton [this message]
2022-05-10 16:52 ` Minchan Kim
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