On Mar 22, 2013, at 11:12 AM, Roman Mamedov <r...@romanrm.ru> wrote:
>> The "disk" is an iscsi disk that in my benchmarks performs roughly like a >> local raid with 2-3 SATA disks. > > I think you should re-verify if this is still the case. Maybe your block > device performance suddenly plummeted for some other unrelated issue? > > The simplest test would be "hdparm -t /dev/sdc". If I boot without mounting the btrfs file system then I get: Timing buffered disk reads: 268 MB in 3.01 seconds = 89.14 MB/sec Timing buffered disk reads: 268 MB in 3.02 seconds = 88.86 MB/sec Timing buffered disk reads: 268 MB in 3.01 seconds = 89.18 MB/sec Timing buffered disk reads: 266 MB in 3.00 seconds = 88.59 MB/sec Timing buffered disk reads: 272 MB in 3.01 seconds = 90.26 MB/sec Timing buffered disk reads: 268 MB in 3.01 seconds = 88.99 MB/sec Timing buffered disk reads: 266 MB in 3.01 seconds = 88.48 MB/sec I also made a new LUN on the iscsi target and tested with bonnie++ on a fresh btrfs file system on that device and got reasonable results (mounted without compression to make sure that wouldn't make it cheat on actual IO): Version 1.96 ------Sequential Output------ --Sequential Input- --Random- Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP gunnarr.bn.d 15456M 476 99 122194 13 42724 8 2327 95 113553 14 494.8 21 Latency 44109us 465ms 268ms 19309us 300ms 1161ms Version 1.96 ------Sequential Create------ --------Random Create-------- gunnarr.bn.dev -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 14550 57 +++++ +++ 20353 67 15617 61 +++++ +++ 19165 72 Latency 295us 566us 532us 373us 29us 561us For what it's worth the iscsi target (a Synology box, some sort of linux) shows lower load running bonnie++ than when the other btrfs file system is mounted with the btrfs-cleaner process running (and nothing happening). Ask-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html