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Jan Kara authored
Patch series "Speed up page cache truncation", v1. When rebasing our enterprise distro to a newer kernel (from 4.4 to 4.12) we have noticed a regression in bonnie++ benchmark when deleting files. Eventually we have tracked this down to a fact that page cache truncation got slower by about 10%. There were both gains and losses in the above interval of kernels but we have been able to identify that commit 83929372 ("filemap: prepare find and delete operations for huge pages") caused about 10% regression on its own. After some investigation it didn't seem easily possible to fix the regression while maintaining the THP in page cache functionality so we've decided to optimize the page cache truncation path instead to make up for the change. This series is a result of that effort. Patch 1 is an easy speedup of cancel_dirty_page(). Patches 2-6 refactor page cache truncation code so that it is easier to batch radix tree operations. Patch 7 implements batching of deletes from the radix tree which more than makes up for the original regression. This patch (of 7): cancel_dirty_page() does quite some work even for clean pages (fetching of mapping, locking of memcg, atomic bit op on page flags) so it accounts for ~2.5% of cost of truncation of a clean page. That is not much but still dumb for something we don't need at all. Check whether a page is actually dirty and avoid any work if not. Link: http://lkml.kernel.org/r/20171010151937.26984-2-jack@suse.czSigned-off-by:
Jan Kara <jack@suse.cz> Acked-by:
Mel Gorman <mgorman@suse.de> Reviewed-by:
Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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