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From: Kevin Wolf <kwolf@redhat.com>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] virtio-blk: Avoid zeroing every request structure
Date: Tue, 18 May 2010 11:36:55 +0200	[thread overview]
Message-ID: <4BF25FB7.9020007@redhat.com> (raw)
In-Reply-To: <1273873950-25756-1-git-send-email-stefanha@linux.vnet.ibm.com>

Am 14.05.2010 23:52, schrieb Stefan Hajnoczi:
> The VirtIOBlockRequest structure is about 40 KB in size.  This patch
> avoids zeroing every request by only initializing fields that are read.
> The other fields are either written to or may not be used at all.
> 
> Oprofile shows about 10% of CPU samples in memset called by
> virtio_blk_alloc_request().  The workload is
> dd if=/dev/vda of=/dev/null iflag=direct bs=8k running concurrently 4
> times.  This patch makes memset disappear to the bottom of the profile.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Thanks, applied to the block branch.

Kevin

  parent reply	other threads:[~2010-05-18  9:41 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-14 21:52 [Qemu-devel] [PATCH] virtio-blk: Avoid zeroing every request structure Stefan Hajnoczi
2010-05-16 13:25 ` Christoph Hellwig
2010-05-16 15:01   ` Stefan Hajnoczi
2010-05-18  9:36 ` Kevin Wolf [this message]
2010-05-18 15:46 ` Jes Sorensen
2010-05-18 16:26   ` Alexander Graf
2010-05-18 16:29     ` Anthony Liguori
2010-05-18 16:31       ` Alexander Graf
2010-05-29 13:07         ` Jamie Lokier
2010-05-18 16:37 ` Corentin Chary
2010-05-18 19:02   ` Stefan Hajnoczi
2010-05-18 19:55     ` Corentin Chary
2010-05-18 20:43       ` Stefan Hajnoczi
2010-05-21 11:17         ` Stefan Hajnoczi
2010-05-21 17:37           ` [Qemu-devel] [PATCH 0/2] Tidy qemu_malloc Richard Henderson
2010-05-28 22:08             ` Aurelien Jarno
2010-05-21 17:37           ` [Qemu-devel] [PATCH 1/2] Use calloc in qemu_mallocz Richard Henderson
2010-05-21 17:37           ` [Qemu-devel] [PATCH 2/2] linux-user: Use qemu-malloc.c Richard Henderson

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