From: PANKAJ RAWAT <pankajr141@gmail.com>
To: qemu-devel <qemu-devel@nongnu.org>
Subject: [Qemu-devel] effect of cluster_size on qcow2 performance during expansion
Date: Thu, 23 Feb 2012 13:54:15 +0530 [thread overview]
Message-ID: <CABZruFAisb9a-xuY7ORWFv0LvV0FpDA8fjzmtHvft-X4KYVBbA@mail.gmail.com> (raw)
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Hi all
I have been working on the qcow2 image format ,
In theory regarding cluster size it is written that as the size of cluster
increase performance should increase.
But something surprising happen The performance is degrading as the size of
cluster increased from *64K* to *1M* or *2M* ( during expansion of qcow2
image)
By expansion i mean that initially qcow2 image is small in size and size
increases when we perform any write operation on it.
Here are the reading taken through fio tool during write operation
*Cluster size : 32K 587Mb/sec (aggrb MB/sec)
*
*
*
*Cluster size : 64K 697Mb/sec** (aggrb MB/sec)*
*
Cluster size : 1M 440Mb/sec* *(aggrb MB/sec)*
*
*
* Cluster size : 2M 289Mb/sec** (aggrb MB/sec)*
as in above it can bee seen that the 64k is performing better
can any one tell why ?
--
*Pankaj Rawat*
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next reply other threads:[~2012-02-23 8:24 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-23 8:24 PANKAJ RAWAT [this message]
2012-02-23 9:17 ` [Qemu-devel] effect of cluster_size on qcow2 performance during expansion Stefan Hajnoczi
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