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
next prev 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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