On Mon, Jun 03, 2013 at 01:02:10PM -0700, Dave Hansen wrote: > >From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > >This was a suggestion from Mel: > > http://lkml.kernel.org/r/20120914085634.GM11157@xxxxxxxxx > >Any pages we collect on 'batch_for_mapping_removal' will have >their lock_page() held during the duration of their stay on the >list. If some other user is trying to get at them during this >time, they might end up having to wait. > >This ensures that we drain the batch if we are about to perform a >pageout() or congestion_wait(), either of which will take some >time. We expect this to help mitigate the worst of the latency >increase that the batching could cause. > >I added some statistics to the __remove_mapping_batch() code to >track how large the lists are that we pass in to it. With this >patch, the average list length drops about 10% (from about 4.1 to >3.8). The workload here was a make -j4 kernel compile on a VM >with 200MB of RAM. > >I've still got the statistics patch around if anyone is >interested. > >Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> >--- > Reviewed-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> > linux.git-davehans/mm/vmscan.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > >diff -puN mm/vmscan.c~drain-batch-list-during-long-operations mm/vmscan.c >--- linux.git/mm/vmscan.c~drain-batch-list-during-long-operations 2013-06-03 12:41:31.661762522 -0700 >+++ linux.git-davehans/mm/vmscan.c 2013-06-03 12:41:31.665762700 -0700 >@@ -1001,6 +1001,16 @@ static unsigned long shrink_page_list(st > if (!sc->may_writepage) > goto keep_locked; > >+ /* >+ * We hold a bunch of page locks on the batch. >+ * pageout() can take a while, so drain the >+ * batch before we perform pageout. >+ */ >+ nr_reclaimed += >+ __remove_mapping_batch(&batch_for_mapping_rm, >+ &ret_pages, >+ &free_pages); >+ > /* Page is dirty, try to write it out here */ > switch (pageout(page, mapping, sc)) { > case PAGE_KEEP: >_ > >-- >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> -- 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>