linux-kernel - Re: [PATCH] mm: vmscan: avoid a unnecessary reschedule in shrink

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Message-ID: <20201016134457.GM22589@dhcp22.suse.cz>
Date:   Fri, 16 Oct 2020 15:44:57 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Tianxianting <tian.xianting@....com>
Cc:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: vmscan: avoid a unnecessary reschedule in
 shrink_slab()

On Fri 16-10-20 13:20:41, Tianxianting wrote:
> Thanks
> I understood what you said :)
> But whether it is proper to check reschedule in every loop when lock is taken? 

I do not see any actual problem TBH. cond_resched is mostly to increase
interactivity for non preemptible kernel. It can reduce throughput but
this is a memory reclaim path and I do not expect this to contribute to
any moderate hot paths. Direct reclaim doesn't really count as a hot
path.

-- 
Michal Hocko
SUSE Labs