The patch titled readahead: reduce unnecessary mmap_miss increases has been removed from the -mm tree. Its filename was readahead-reduce-unnecessary-mmap_miss-increases.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: readahead: reduce unnecessary mmap_miss increases From: Andi Kleen <ak@xxxxxxxxxxxxxxx> The original INT_MAX is too large, reduce it to - avoid unnecessarily dirtying/bouncing the cache line - restore mmap read-around faster on changed access pattern Background: in the mosbench exim benchmark which does multi-threaded page faults on shared struct file, the ra->mmap_miss updates are found to cause excessive cache line bouncing on tmpfs. The ra state updates are needless for tmpfs because it actually disabled readahead totally (shmem_backing_dev_info.ra_pages == 0). Tested-by: Tim Chen <tim.c.chen@xxxxxxxxx> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN mm/filemap.c~readahead-reduce-unnecessary-mmap_miss-increases mm/filemap.c --- a/mm/filemap.c~readahead-reduce-unnecessary-mmap_miss-increases +++ a/mm/filemap.c @@ -1566,7 +1566,8 @@ static void do_sync_mmap_readahead(struc return; } - if (ra->mmap_miss < INT_MAX) + /* Avoid banging the cache line if not needed */ + if (ra->mmap_miss < MMAP_LOTSAMISS * 10) ra->mmap_miss++; /* _ Patches currently in -mm which might be from ak@xxxxxxxxxxxxxxx are origin.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html