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... :) --D > -- > Jens Axboe >
