From: Tang Junhui <tang.junhui@xxxxxxxxxx> >On 01/02/2018 12:53 AM, tang.junhui@xxxxxxxxxx wrote: >> If no front-end I/O coming, would this cause write-back IOs one by one >> (one write-back IO issued must after the completion of the previous IO)? >> though with zero delay time, is the write-back performance still good? > >Yes-- this speeds up writeback during idle from 4k/sec to about 10MB/sec >on my slow 5400RPM disk. (It writes back at about 20MB/sec with deep >queues in the same scenario). So in this case it's about 2500x faster >than current idle writeback, but half as fast as writeback with full >device utilization. > >With only one I/O outstanding at a time, if front-end I/O starts latency >for the first request is still good. > OK, LGTM. Reviewed-by: Tang Junhui <tang.junhui@xxxxxxxxxx> Thanks, Tang Junhui
