From: Eric Blake <eblake@redhat.com>
To: Peter Lieven <pl@kamp.de>, Stefan Hajnoczi <stefanha@gmail.com>
Cc: kwolf@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org,
stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCHv3 1.8 8/9] qemu-img: increase min_sparse to 128 sectors (64kb)
Date: Wed, 04 Dec 2013 19:12:15 -0700 [thread overview]
Message-ID: <529FE0FF.5040503@redhat.com> (raw)
In-Reply-To: <529F5C56.20906@kamp.de>
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On 12/04/2013 09:46 AM, Peter Lieven wrote:
>> I guess a sane size would be cluster size. For a raw file 4 KB is
>> reasonable since that's the file system block size.
> in case of iscsi the cluster size could be much too high as for example
> my storage has a cluster_size of 15MB.
>>
>> Is it necessary to increase to 64 KB here?
> No, its indepent of the rest. Paolo suggested to increase it and I can confirm
> that for my usage case its faster than 4K.
At least on NTFS file systems, 64k is the minimum size of a hole in a
sparse file. While many file systems support smaller holes, there are
definitely systems where trying to detect smaller holes only results in
wasted efforts. Is it worth making the default dynamic based on stat()
information regarding optimum IO size for the given destination file system?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2013-12-05 2:12 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-27 10:07 [Qemu-devel] [PATCHv3 1.8 0/9] qemu-img convert optimizations Peter Lieven
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 1/9] qemu-img: add support for skipping zeroes in input during convert Peter Lieven
2013-11-27 10:17 ` Paolo Bonzini
2013-12-04 16:46 ` Stefan Hajnoczi
2013-12-04 16:51 ` Peter Lieven
2013-12-05 10:30 ` Stefan Hajnoczi
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 2/9] qemu-img: fix usage instruction for qemu-img convert Peter Lieven
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 3/9] block/iscsi: set bdi->cluster_size Peter Lieven
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 4/9] block: add opt_transfer_length to BlockLimits Peter Lieven
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 5/9] block/iscsi: set bs->bl.opt_transfer_length Peter Lieven
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 6/9] qemu-img: dynamically adjust iobuffer size during convert Peter Lieven
2013-12-05 13:30 ` Eric Blake
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 7/9] qemu-img: round down request length to an aligned sector Peter Lieven
2013-12-04 15:49 ` Stefan Hajnoczi
2013-12-04 15:56 ` Peter Lieven
2013-12-05 10:33 ` Stefan Hajnoczi
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 8/9] qemu-img: increase min_sparse to 128 sectors (64kb) Peter Lieven
2013-12-04 16:43 ` Stefan Hajnoczi
2013-12-04 16:46 ` Peter Lieven
2013-12-05 2:12 ` Eric Blake [this message]
2013-12-05 4:55 ` Peter Lieven
2013-12-05 10:35 ` Stefan Hajnoczi
2013-11-27 10:07 ` [Qemu-devel] [PATCHv3 1.8 9/9] qemu-img: decrease progress update interval on convert Peter Lieven
2013-12-05 12:15 ` [Qemu-devel] [PATCHv3 1.8 0/9] qemu-img convert optimizations Stefan Hajnoczi
2013-12-05 14:55 ` Peter Lieven
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