From: Matthew Wilcox <willy@infradead.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-mm@kvack.org, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Andres Freund <andres@anarazel.de>
Subject: Re: [PATCH] block: Skip the folio lock if the folio is already dirty
Date: Fri, 24 Jan 2025 22:49:34 +0000 [thread overview]
Message-ID: <Z5QY_hpDZ84KN3In@casper.infradead.org> (raw)
In-Reply-To: <20250124224832.322771-1-willy@infradead.org>
On Fri, Jan 24, 2025 at 10:48:29PM +0000, Matthew Wilcox (Oracle) wrote:
> Postgres sees significant contention on the hashed folio waitqueue lock
> when performing direct I/O to 1GB hugetlb pages. This is because we
> mark the destination pages as dirty, and the locks end up 512x more
> contended with 1GB pages than with 2MB pages.
>
> We can skip the locking if the folio is already marked as dirty.
> The writeback path clears the dirty flag before commencing writeback,
> if we see the dirty flag set, the data written to the folio will be
> written back.
>
> In one test, throughput increased from 18GB/s to 20GB/s and moved the
> bottleneck elsewhere.
>
> Reported-by: Andres Freund <andres@anarazel.de>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
... this is the wrong version of the patch *facepalm*
next prev parent reply other threads:[~2025-01-24 22:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-24 22:48 Matthew Wilcox (Oracle)
2025-01-24 22:49 ` Matthew Wilcox [this message]
2025-01-27 7:52 ` Hannes Reinecke
2025-01-24 22:51 Matthew Wilcox (Oracle)
2025-01-28 5:58 ` Christoph Hellwig
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