Messages in this thread | | | Date | Sat, 18 May 2013 23:15:34 +0200 | From | Zlatko Calusic <> | Subject | Re: [PATCH 0/9] Reduce system disruption due to kswapd V4 |
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On 15.05.2013 22:37, Andrew Morton wrote: >> >> 3.10.0-rc1 3.10.0-rc1 >> vanilla lessdisrupt-v4 >> Page Ins 1234608 101892 >> Page Outs 12446272 11810468 >> Swap Ins 283406 0 >> Swap Outs 698469 27882 >> Direct pages scanned 0 136480 >> Kswapd pages scanned 6266537 5369364 >> Kswapd pages reclaimed 1088989 930832 >> Direct pages reclaimed 0 120901 >> Kswapd efficiency 17% 17% >> Kswapd velocity 5398.371 4635.115 >> Direct efficiency 100% 88% >> Direct velocity 0.000 117.817 >> Percentage direct scans 0% 2% >> Page writes by reclaim 1655843 4009929 >> Page writes file 957374 3982047 >> Page writes anon 698469 27882 >> Page reclaim immediate 5245 1745 >> Page rescued immediate 0 0 >> Slabs scanned 33664 25216 >> Direct inode steals 0 0 >> Kswapd inode steals 19409 778 > > The reduction in inode steals might be a significant thing? > prune_icache_sb() does invalidate_mapping_pages() and can have the bad > habit of shooting down a vast number of pagecache pages (for a large > file) in a single hit. Did this workload use large (and clean) files? > Did you run any test which would expose this effect? >
I did not run specific tests, but I believe I observed exactly this issue on the real workload, where even at a moderate load sudden frees of pagecache happen quite often. I've attached a small graph where it can be easily seen. The snapshot was taken while the server was running an unpatched Linus kernel. After the Mel's patch series is applied, I can't see anything similar. So it seems that this issue is completely gone, Mel's done a wonderful job.
And BTW, V4 continues to be rock stable, running here on many different machines, so I look forward seeing this code merged in 3.11. -- Zlatko [unhandled content-type:image/png] | |