Subject: [merged] mm-readaheadc-fix-readahead-failure-for-memoryless-numa-nodes-and-limit-readahead-pages.patch removed from -mm tree To: raghavendra.kt@xxxxxxxxxxxxxxxxxx,fengguang.wu@xxxxxxxxx,jack@xxxxxxx,rientjes@xxxxxxxxxx,torvalds@xxxxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Fri, 04 Apr 2014 12:32:16 -0700 The patch titled Subject: mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages has been removed from the -mm tree. Its filename was mm-readaheadc-fix-readahead-failure-for-memoryless-numa-nodes-and-limit-readahead-pages.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx> Subject: mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages Currently max_sane_readahead() returns zero on the cpu whose NUMA node has no local memory which leads to readahead failure. Fix this readahead failure by returning minimum of (requested pages, 512). Users running applications on a memory-less cpu which needs readahead such as streaming application see considerable boost in the performance. Result: fadvise experiment with FADV_WILLNEED on a PPC machine having memoryless CPU with 1GB testfile (12 iterations) yielded around 46.66% improvement. fadvise experiment with FADV_WILLNEED on a x240 machine with 1GB testfile 32GB* 4G RAM numa machine (12 iterations) showed no impact on the normal NUMA cases w/ patch. Kernel Avg Stddev base 7.4975 3.92% patched 7.4174 3.26% [Andrew: making return value PAGE_SIZE independent] Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx> Acked-by: Jan Kara <jack@xxxxxxx> Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/readahead.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN mm/readahead.c~mm-readaheadc-fix-readahead-failure-for-memoryless-numa-nodes-and-limit-readahead-pages mm/readahead.c --- a/mm/readahead.c~mm-readaheadc-fix-readahead-failure-for-memoryless-numa-nodes-and-limit-readahead-pages +++ a/mm/readahead.c @@ -233,14 +233,14 @@ int force_page_cache_readahead(struct ad return 0; } +#define MAX_READAHEAD ((512*4096)/PAGE_CACHE_SIZE) /* * Given a desired number of PAGE_CACHE_SIZE readahead pages, return a * sensible upper limit. */ unsigned long max_sane_readahead(unsigned long nr) { - return min(nr, (node_page_state(numa_node_id(), NR_INACTIVE_FILE) - + node_page_state(numa_node_id(), NR_FREE_PAGES)) / 2); + return min(nr, MAX_READAHEAD); } /* _ Patches currently in -mm which might be from raghavendra.kt@xxxxxxxxxxxxxxxxxx are origin.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