From: Christoph Hellwig <hch@lst.de>
To: Damien Le Moal <damien.lemoal@wdc.com>
Cc: linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2] block: Fix __blkdev_issue_zeroout loop
Date: Wed, 5 Jul 2017 19:26:16 +0200 [thread overview]
Message-ID: <20170705172616.GA5417@lst.de> (raw)
In-Reply-To: <20170704082702.15727-1-damien.lemoal@wdc.com>
On Tue, Jul 04, 2017 at 05:27:02PM +0900, Damien Le Moal wrote:
> The BIO issuing loop in __blkdev_issue_zeroout() is allocating BIOs
> with a maximum number of bvec (pages) equal to
>
> min(nr_sects, (sector_t)BIO_MAX_PAGES)
>
> This works since the BIO will always be limited to the absolute maximum
> number of pages but this is ineficient as too many bvec entries may be
> requested since different units (number of sectors vs number of pages)
> are used in the min() operation. Fix this by correctly using the same
> unit (number of pages), making sure that this number is at least 1 for
> cases where the number of sectors is less that the number of sectors in
> a page.
>
> Also remove a trailing space after the bit shift in the internal loop
> min() call.
Can you move the nr sectors calculation into a helper and add some
comments?
next prev parent reply other threads:[~2017-07-05 17:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-04 8:27 [PATCH v2] block: Fix __blkdev_issue_zeroout loop Damien Le Moal
2017-07-05 17:26 ` Christoph Hellwig [this message]
2017-07-05 23:50 ` Damien Le Moal
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