On 06/25/2012 02:39 PM, MORITA Kazutaka wrote: > Why do you assume the request size is 512k? Maybe I'm missing > something, and I'm fine with it if 8 is not too small. This is default for any installation of Linux distro. At least for me I don't see any number bigger than 512, even for ssd. tailai.ly at taobao:~$ cat /sys/block/sda/queue/max_sectors_kb 512 But this value is tunable, though internal IO stack doesn't honor this value faithfully ( I have tried change it to 4096(4M for req size), but I noticed that Guest can only issue as big as around 3M req. Thanks, Yuan |