On Thu, 4 Oct 2012, Konstantin Khlebnikov wrote: > Here results of my test. Workload isn't very realistic, but at least it > threaded: compiling linux-3.6 with defconfig in 16 threads on tmpfs, > 512mb ram, dualcore cpu, ordinary hard disk. (test script in attachment) > > average results for ten runs: > > RA=3 RA=0 RA=1 RA=2 RA=4 Hugh Shaohua > real time 500 542 528 519 500 523 522 > user time 738 737 735 737 739 737 739 > sys time 93 93 91 92 96 92 93 > pgmajfault 62918 110533 92454 78221 54342 86601 77229 > pgpgin 2070372 795228 1034046 1471010 3177192 1154532 1599388 > pgpgout 2597278 2022037 2110020 2350380 2802670 2286671 2526570 > pswpin 462747 138873 202148 310969 739431 232710 341320 > pswpout 646363 502599 524613 584731 697797 568784 628677 > > So, last two columns shows mostly equal results: +4.6% and +4.4% in > comparison to vanilla kernel with RA=3, but your version shows more stable > results (std-error 2.7% against 4.8%) (all this numbers in huge table in > attachment) Thanks for doing this, Konstantin, but I'm stuck for anything much to say! Shaohua and I are both about 4.5% bad for this particular test, but I'm more consistently bad - hurrah! I suspect (not a convincing argument) that if the test were just slightly different (a little more or a little less memory, SSD instead of hard disk, diskcache instead of tmpfs), then it would come out differently. Did you draw any conclusions from the numbers you found? I haven't done any more on this in the last few days, except to verify that once an anon_vma is judged random with Shaohua's, then it appears to be condemned to no-readahead ever after. That's probably something that a hack like I had in mine would fix, but that addition might change its balance further (and increase vma or anon_vma size) - not tried yet. All I want to do right now, is suggest to Andrew that he hold Shaohua's patch back from 3.7 for the moment: I'll send a response to Sep 7th's mm-commits mail to suggest that - but no great disaster if he ignores me. Hugh > > Numbers from your tests formatted into table for better readability > > HDD Vanilla Shaohua RA=3 RA=0 RA=4 > SEQ, ANON 73921 76210 75611 121542 77950 > SEQ, SHMEM 73601 73176 73855 118322 73534 > RND, ANON 895392 831243 871569 841680 863871 > RND, SHMEM 1058375 1053486 827935 756489 834804 > > SDD Vanilla Shaohua RA=3 RA=0 RA=4 > SEQ, ANON 24634 24198 24673 70018 21125 > SEQ, SHMEM 24959 24932 25052 69678 21387 > RND, ANON 43014 26146 28075 25901 28686 > RND, SHMEM 45349 45215 28249 24332 28226 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>