On Sat, 24 Dec 2011 07:45:03 +1100 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Fri, Dec 23, 2011 at 03:04:02PM +0400, nowhere wrote: > > В Пт., 23/12/2011 в 21:20 +1100, Dave Chinner пишет: > > > On Fri, Dec 23, 2011 at 01:01:20PM +0400, nowhere wrote: > > > > В Чт., 22/12/2011 в 09:55 +1100, Dave Chinner пишет: > > > > > On Wed, Dec 21, 2011 at 10:52:49AM +0100, Michal Hocko wrote: > > Here is the report of trace-cmd while dd'ing > > https://80.237.6.56/report-dd.xz > > Ok, it's not a shrink_slab() problem - it's just being called ~100uS > by kswapd. The pattern is: > > - reclaim 94 (batches of 32,32,30) pages from iinactive list > of zone 1, node 0, prio 12 > - call shrink_slab > - scan all caches > - all shrinkers return 0 saying nothing to shrink > - 40us gap > - reclaim 10-30 pages from inactive list of zone 2, node 0, prio 12 > - call shrink_slab > - scan all caches > - all shrinkers return 0 saying nothing to shrink > - 40us gap > - isolate 9 pages from LRU zone ?, node ?, none isolated, none freed > - isolate 22 pages from LRU zone ?, node ?, none isolated, none freed > - call shrink_slab > - scan all caches > - all shrinkers return 0 saying nothing to shrink > 40us gap > > And it just repeats over and over again. After a while, nid=0,zone=1 > drops out of the traces, so reclaim only comes in batches of 10-30 > pages from zone 2 between each shrink_slab() call. > > The trace starts at 111209.881s, with 944776 pages on the LRUs. It > finishes at 111216.1 with kswapd going to sleep on node 0 with > 930067 pages on the LRU. So 7 seconds to free 15,000 pages (call it > 2,000 pages/s) which is awfully slow.... > > vmscan gurus - time for you to step in now... > Can you show /proc/zoneinfo ? I want to know each zone's size. Below is my memo. In trace log, priority = 11 or 12. Then, I think kswapd can reclaim memory to satisfy "sc.nr_reclaimed >= SWAP_CLUSTER_MAX" condition and loops again. Seeing balance_pgdat() and trace log, I guess it does wake up shrink_zone(zone=0(DMA?)) => nothing to reclaim. shrink_slab() shrink_zone(zone=1(DMA32?)) => reclaim 32,32,31 pages shrink_slab() shrink_zone(zone=2(NORMAL?)) => reclaim 13 pages. srhink_slab() sleep or retry. Why shrink_slab() need to be called frequently like this ? BTW. I'm sorry if I miss something ...Why only kswapd reclaims memory while 'dd' operation ? (no direct relcaim by dd.) Is this log record cpu hog after 'dd' ? Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>