Date:   Thu, 25 Nov 2021 03:30:44 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Hao Lee <haolee.swjtu@gmail.com>
Cc:     Michal Hocko <mhocko@suse.com>, Linux MM <linux-mm@kvack.org>,
        Johannes Weiner <hannes@cmpxchg.org>, vdavydov.dev@gmail.com,
        Shakeel Butt <shakeelb@google.com>, cgroups@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: reduce spinlock contention in release_pages()
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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@suse.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?