Commit e0de0206a2a37cd3e0ba9954d9f863e11d6d1782
1 parent
ba8f5baba7
[PATCH] cfq-iosched: check busy queues before deciding we are idle
For just one busy queue (like async write out), we often overlooked that we could queue more io and decided we were idle instead. This causes us quite a bit of performance loss. Signed-off-by: Jens Axboe <axboe@suse.de>
Showing 1 changed file with 7 additions and 0 deletions Side-by-side Diff
block/cfq-iosched.c
| ... | ... | @@ -879,6 +879,13 @@ |
| 879 | 879 | cfqq = list_entry_cfqq(cfqd->cur_rr.next); |
| 880 | 880 | |
| 881 | 881 | /* |
| 882 | + * If no new queues are available, check if the busy list has some | |
| 883 | + * before falling back to idle io. | |
| 884 | + */ | |
| 885 | + if (!cfqq && !list_empty(&cfqd->busy_rr)) | |
| 886 | + cfqq = list_entry_cfqq(cfqd->busy_rr.next); | |
| 887 | + | |
| 888 | + /* | |
| 882 | 889 | * if we have idle queues and no rt or be queues had pending |
| 883 | 890 | * requests, either allow immediate service if the grace period |
| 884 | 891 | * has passed or arm the idle grace timer |