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From: Matthew Wilcox <willy@infradead.org>
To: Tony Battersby <tonyb@cybernetics.com>
Cc: Song Liu <song@kernel.org>, Yu Kuai <yukuai3@huawei.com>,
	Christian Brauner <brauner@kernel.org>,
	"Darrick J. Wong" <djwong@kernel.org>,
	linux-raid@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] iomap: align writeback to RAID stripe boundaries
Date: Tue, 29 Jul 2025 19:38:20 +0100	[thread overview]
Message-ID: <aIkVHBsC6M5ZHGzQ@casper.infradead.org> (raw)
In-Reply-To: <55deda1d-967d-4d68-a9ba-4d5139374a37@cybernetics.com>

On Tue, Jul 29, 2025 at 12:13:42PM -0400, Tony Battersby wrote:
> Improve writeback performance to RAID-4/5/6 by aligning writes to stripe
> boundaries.  This relies on io_opt being set to the stripe size (or
> a multiple) when BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE is set.

When you say "aligning writes to stripe boundaries", what you actually
seem to be doing here is sending writes down once we hit a write stripe
boundary, instead of accumulating writes that cross stripe boundaries.
Do I understand correctly?

If so, the performance gain we see here is presumably from the DM/MD
driver not having to split bios that cross boundaries?

Further, wouldn't it be simpler to just put a new condition in
iomap_can_add_to_ioend() rather than turning iomap_add_to_ioend()
into a nested loop?


  reply	other threads:[~2025-07-29 18:38 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-29 16:13 [PATCH 2/2] iomap: align writeback to RAID stripe boundaries Tony Battersby
2025-07-29 18:38 ` Matthew Wilcox [this message]
2025-07-29 19:01   ` Tony Battersby
2025-07-29 19:17     ` Matthew Wilcox
2025-07-29 20:12       ` Tony Battersby
2025-07-30  0:52 ` Dave Chinner
2025-07-30 14:14 ` Christoph Hellwig

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