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From: Joanne Koong <joannelkoong@gmail.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, jack@suse.cz,
	 willy@infradead.org, miklos@szeredi.hu, linux-mm@kvack.org,
	 linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v1] mm: fix writeback regression for strictlimit BDIs
Date: Thu, 26 Mar 2026 10:53:57 -0700	[thread overview]
Message-ID: <CAJnrk1ZTHphV9e=chJD5iHTMDm7F1qqHebn6+Li2cYaggyP6AA@mail.gmail.com> (raw)
In-Reply-To: <acTJLJdrd_T-cOAu@infradead.org>

On Wed, Mar 25, 2026 at 10:50 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Wed, Mar 25, 2026 at 05:13:37PM -0700, Joanne Koong wrote:
> > Commit 64dd89ae01f2 ("mm/block/fs: remove laptop_mode") removed this
> > unconditional writeback kick from balance_dirty_pages():
> >
> >        if (unlikely(!writeback_in_progress(wb)))
> >              wb_start_background_writeback(wb);
>
> Yes, that looks like a bug.
>
> > This fixes the issue by kicking off the flusher if wb_dirty exceeds
> > wb_bg_thresh for strictlimit BDIs. This restores performance back to its
> > original baseline.
>
> What speaks against just reinstating the old-code as-is minus the
> misleading latop_mode comment?
>

I thought those two lines were unnecessary for nonstrictlimited bdis
but after reading Jan's feedback, you're right this should just
reinstate the old code as is.

Thanks,
Joanne


  reply	other threads:[~2026-03-26 17:54 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-26  0:13 Joanne Koong
2026-03-26  5:50 ` Christoph Hellwig
2026-03-26 17:53   ` Joanne Koong [this message]
2026-03-26  8:48 ` Jan Kara
2026-03-26 17:58   ` Joanne Koong

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