linux-kernel - Re: [PATCH] block/psi: remove PSI annotations from submit

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Message-ID: <6231608b.1c69fb81.961b0.2e1a@mx.google.com>
Date:   Wed, 16 Mar 2022 03:59:05 +0000
From:   CGEL <cgel.zte@...il.com>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     axboe@...nel.dk, viro@...iv.linux.org.uk,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, akpm@...ux-foundation.org,
        Yang Yang <yang.yang29@....com.cn>,
        Ran Xiaokai <ran.xiaokai@....com.cn>
Subject: Re: [PATCH] block/psi: remove PSI annotations from submit_bio

On Wed, Mar 09, 2022 at 02:18:19PM -0500, Johannes Weiner wrote:
> On Wed, Mar 09, 2022 at 09:43:24AM +0000, cgel.zte@...il.com wrote:
> > From: Yang Yang <yang.yang29@....com.cn>
> > 
> > psi tracks the time spent submitting the IO of refaulting pages[1].
> > But after we tracks refault stalls from swap_readpage[2][3], there
> > is no need to do so anymore. Since swap_readpage already includes
> > IO submitting time.
> > 
> > [1] commit b8e24a9300b0 ("block: annotate refault stalls from IO submission")
> > [2] commit 937790699be9 ("mm/page_io.c: annotate refault stalls from swap_readpage")
> > [3] commit 2b413a1a728f ("mm: page_io: fix psi memory pressure error on cold swapins")
> > 
> > Signed-off-by: Yang Yang <yang.yang29@....com.cn>
> > Reviewed-by: Ran Xiaokai <ran.xiaokai@....com.cn>
> 
> It's still needed by file cache refaults!
> 
> NAK
What about submit_bio() only counts file cache refaults?
This will reduce redundant calling of psi_memstall_enter()
for swap_readpage().