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From: | Anton Nefedov |
Subject: | Re: [Qemu-block] [PATCH 0/7] qcow2: Reduce the number of I/O ops when doing COW |
Date: | Fri, 26 May 2017 15:47:55 +0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 |
On 05/26/2017 01:17 PM, Kevin Wolf wrote:
Am 24.05.2017 um 18:09 hat Anton Nefedov geschrieben:I agree; as mentioned we have similar patches and they don't conflict much. We noticed a performance regression on HDD though, for the presumably optimized case (random 4k write over a large backed image); so the patches were put on hold.You're talking about your own patches that should do the same thing, right? Can you re-do the same test with Berto's patches? Maybe there was just an implementation glitch in yours. This approach should very obviously result in a performance improvement, and the patches are relatively simple, so I'm very much inclined to merge this as soon as possible. Kevin
Tried the another machine; about 10% improvement here address@hidden centos-7.3-x86_64]# qemu-img info ./harddisk2.hdd image: ./harddisk2.hdd file format: qcow2 virtual size: 2.0G (2147483648 bytes) disk size: 260K cluster_size: 65536 backing file: harddisk2.hdd.base (actual path: ./harddisk2.hdd.base) Format specific information: compat: 1.1 lazy refcounts: false refcount bits: 16 corrupt: false address@hidden centos-7.3-x86_64]# qemu-img info ./harddisk2.hdd.base image: ./harddisk2.hdd.base file format: qcow2 virtual size: 2.0G (2147483648 bytes) disk size: 2.0G cluster_size: 65536 Format specific information: compat: 1.1 lazy refcounts: true refcount bits: 16 corrupt: false address@hidden centos-7.3-x86_64]# filefrag ./harddisk2.hdd.base ./harddisk2.hdd.base: 3 extents found address@hidden ~]# fio --name=randwrite --blocksize=4k --filename=/dev/sdb --rw=randwrite --direct=1 --ioengine=libaio --size=2g --io_size=32m /* master */ write: io=32768KB, bw=372785B/s, iops=91, runt= 90010msec /* Berto's patches */ write: io=32768KB, bw=404304B/s, iops=98, runt= 82993msec /Anton
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