On Thu 25 May 2017 01:48:39 PM CEST, Alberto Garcia wrote: >>>> I agree; as mentioned we have similar patches and they don't >>>> conflict much. We noticed a performance regression on HDD though, >>>> for the presumably optimized case (random 4k write over a large >>>> backed image); so the patches were put on hold. >>> >>> Interesting, I think that scenario was noticeably faster in my >>> tests. What cluster size(s) and image size(s) were you using? >>> >> 64k cluster, 2g image, write 32m in portions of 4k at random offsets > > I just tried that and the optimized case performs better (as > expected), almost twice as fast in fact: > > write: io=32892KB, bw=162944B/s, iops=39, runt=206705msec > write: io=32892KB, bw=309256B/s, iops=75, runt=108911msec > > I'll try in a different machine.
I made more tests of that same scenario with a different HDD: write: io=32892KB, bw=588588B/s, iops=143, runt= 57224msec write: io=32892KB, bw=779951B/s, iops=190, runt= 43184msec And here are the results without a backing file: write: io=32892KB, bw=1510.2KB/s, iops=377, runt= 21781msec write: io=32892KB, bw=5417.1KB/s, iops=1354, runt= 6071msec Berto
