Anthony Liguori wrote: > Laurent Vivier wrote: >> Hi, >> >> I made some benchmarks with dbench on linux/KVM. >> >> IDE means I use an image disk with "-hda" >> SCSI means I use an image disk with "-sda" >> (see the patch I proposed on qemu list: >> http://www.mail-archive.com/[EMAIL PROTECTED]/msg08679.html ) >> >> threads KVM-21 KVM-21 KVM-24 KVM-24 KVM-25 KVM-25 >> IDE SCSI IDE SCSI IDE SCSI >> >> 1 215.272 94.8775 318.626 319.533 307.111 331.757 >> 2 212.061 91.3193 313.217 315.163 314.577 323.715 >> 4 197.586 81.7551 291.752 276.044 292.084 271.191 >> 8 144.814 58.5725 188.819 198.995 168.273 165.564 >> 16 111.505 66.3605 139.824 157.617 150.822 123.671 >> 32 43.4109 15.7386 48.2109 50.4114 59.1074 69.5717 >> 64 21.0567 8.3535 11.3457 19.9483 20.4877 24.5627 >> >> results are in MB/sec >> >> Conclusion: >> >> KVM-25 is really better than KVM-21 >> in most cases, SCSI is better than IDE >> > > Were you using libposix-aio? If not, did you change the aio_init > function in block-raw.c (assuming that you're using a raw disk). > Otherwise, QEMU by default will limit the glibc aio library to a single > thread so you won't see a lot of the benefits of SCSI emulation.
Hi Anthony,
I didn't modify aio_init limit...
I made some benchmarks with liposix-aio, but results are worst with IDE and
crashes with SCSI (because I need to make some additional works).
It's the part on which I work now (to align buffers to avoid redundant buffer
copy and open image disk with O_DIRECT).
Regards,
Laurent
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