On 11/21/19 9:04 AM, Darrick J. Wong wrote: > On Thu, Nov 21, 2019 at 08:56:14AM -0700, Jens Axboe wrote: >> On 11/21/19 3:40 AM, Konstantin Khlebnikov wrote: >>> Requests that triggers flushing volatile writeback cache to disk (barriers) >>> have significant effect to overall performance. >>> >>> Block layer has sophisticated engine for combining several flush requests >>> into one. But there is no statistics for actual flushes executed by disk. >>> Requests which trigger flushes usually are barriers - zero-size writes. >>> >>> This patch adds two iostat counters into /sys/class/block/$dev/stat and >>> /proc/diskstats - count of completed flush requests and their total time. >> >> This makes sense to me, and the "recent" discard addition already proved >> that we're fine extending with more fields. Unless folks object, I'd be >> happy to queue this up for 5.5. > > Looks like a good addition to /me... :) That's all the encouragement I needed, added :-) -- Jens Axboe
