On Tue, Jul 14, 2015 at 05:39:13PM +0300, Gleb Stepanov wrote: > I've measured performance on qcow2 image mounted to nb0 device.
nb0 device? > I run tests and > launch iostat -x 1 command to browse I/O operations. Test consists of > sequential read operations with 1 MB size. I've get following output. > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s > sda 0.00 5.00 0.00 677.00 0.00 22812.00 > sdb 0.00 0.00 0.00 545.00 0.00 0.00 > dm-0 0.00 0.00 0.00 674.00 0.00 22784.00 > dm-1 0.00 0.00 0.00 7.00 0.00 28.00 > dm-2 0.00 0.00 0.00 0.00 0.00 0.00 > nb0 0.00 0.00 432.00 182.00 55296.00 23296.00 > > So, reading produce a lot of write operations. What is the reason why > these write operations occured? > How to determina block size that qemu operates , because if i've > writtien 55 mb with 1 mb blocks > i should get 55 operations instead of 432. Please post details of the benchmark: * fio job file and fio command-line * commands used to launch QEMU or qemu-nbd
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