Messages in this thread | | | Date | Wed, 03 Aug 2011 16:11:51 +0800 | From | Gui Jianfeng <> | Subject | Re: fio posixaio performance problem |
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On 2011-8-3 15:38, Shaohua Li wrote: > 2011/8/3 Gui Jianfeng <guijianfeng@cn.fujitsu.com>: >> Hi, >> >> I ran a fio test to simulate qemu-kvm io behaviour. >> When job number is greater than 2, IO performance is >> really bad. >> >> 1 thread: aggrb=15,129KB/s >> 4 thread: aggrb=1,049KB/s >> >> Kernel: lastest upstream >> >> Any idea? >> >> --- >> [global] >> runtime=30 >> time_based=1 >> size=1G >> group_reporting=1 >> ioengine=posixaio >> exec_prerun='echo 3 > /proc/sys/vm/drop_caches' >> thread=1 >> >> [kvmio-1] >> description=kvmio-1 >> numjobs=4 >> rw=write >> bs=4k >> direct=1 >> filename=/mnt/sda4/1G.img > Hmm, the test runs always about 15M/s at my side regardless how many threads.
CFQ? what's the slice_idle value?
Thanks, Gui
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