On Mon, Jan 23, 2012 at 05:18:57PM +0100, Jan Kara wrote: > requst granularity. Sure, big requests will take longer to complete but > maximum request size is relatively low (512k by default) so writing maximum > sized request isn't that much slower than writing 4k. So it works OK in > practice. Totally unrelated to the writeback, but the merged big 512k requests actually adds up some measurable I/O scheduler latencies and they in turn slightly diminish the fairness that cfq could provide with smaller max request size. Probably even more measurable with SSDs (but then SSDs are even faster). -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
