linux-kernel - Re: [PATCH] mm: reduce spinlock contention in release

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Message-ID: <YZ8DZHERun6Fej2P@casper.infradead.org>
Date:   Thu, 25 Nov 2021 03:30:44 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Hao Lee <haolee.swjtu@...il.com>
Cc:     Michal Hocko <mhocko@...e.com>, Linux MM <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>, vdavydov.dev@...il.com,
        Shakeel Butt <shakeelb@...gle.com>, cgroups@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: reduce spinlock contention in release_pages()

On Thu, Nov 25, 2021 at 11:24:02AM +0800, Hao Lee wrote:
> On Thu, Nov 25, 2021 at 12:31 AM Michal Hocko <mhocko@...e.com> wrote:
> > We do batch currently so no single task should be
> > able to monopolize the cpu for too long. Why this is not sufficient?
> 
> uncharge and unref indeed take advantage of the batch process, but
> del_from_lru needs more time to complete. Several tasks will contend
> spinlock in the loop if nr is very large.

Is SWAP_CLUSTER_MAX too large?  Or does your architecture's spinlock
implementation need to be fixed?