Re: [PATCH 3/7] mm: rework __isolate_lru_page() file/anon filter
From: Hugh Dickins <hughd@google.com>
Date: 2012-03-03 00:23:04
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On Wed, 29 Feb 2012, Konstantin Khlebnikov wrote:
This patch adds file/anon filter bits into isolate_mode_t, this allows to simplify checks in __isolate_lru_page(). Signed-off-by: Konstantin Khlebnikov <redacted>
Almost-Acked-by: Hugh Dickins [off-list ref] with one whitespace nit, and one functional addition requested. I'm perfectly happy with your :?s myself, but some people do dislike them. I'm happy with the switch alternative if it's as efficient: something that surprised me very much when trying to get convincing performance numbers for per-memcg per-zone lru_lock at home... ... __isolate_lru_page() featured astonishly high on the perf report of streaming from files on ext4 on /dev/ram0 to /dev/null, coming immediately below the obvious zeroing and copying: okay, the zeroing and copying were around 30% each, and __isolate_lru_page() down around 2% or below, but even so it seemed very odd that it should feature so high, and any optimizations to it very welcome - unless it was purely some bogus result.
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--- include/linux/mmzone.h | 4 ++++ include/linux/swap.h | 2 +- mm/compaction.c | 5 +++-- mm/vmscan.c | 27 +++++++++++++-------------- 4 files changed, 21 insertions(+), 17 deletions(-)diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index eff4918..2fed935 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h@@ -193,6 +193,10 @@ struct lruvec { #define ISOLATE_UNMAPPED ((__force isolate_mode_t)0x8) /* Isolate for asynchronous migration */ #define ISOLATE_ASYNC_MIGRATE ((__force isolate_mode_t)0x10) +/* Isolate swap-backed pages */ +#define ISOLATE_ANON ((__force isolate_mode_t)0x20) +/* Isolate file-backed pages */ +#define ISOLATE_FILE ((__force isolate_mode_t)0x40)
From the patch you can see that the #defines above yours used a
space where you have used a tab: better to use a space as above.
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@@ -375,7 +376,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, mode |= ISOLATE_ASYNC_MIGRATE; /* Try isolate the page */ - if (__isolate_lru_page(page, mode, 0) != 0) + if (__isolate_lru_page(page, mode) != 0) continue;
I thought you were missing something there, but no, that's rather the case you are simplifying. However...
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diff --git a/mm/vmscan.c b/mm/vmscan.c index af6cfe7..1b70338 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c@@ -1520,6 +1511,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz, isolate_mode |= ISOLATE_UNMAPPED; if (!sc->may_writepage) isolate_mode |= ISOLATE_CLEAN; + if (file) + isolate_mode |= ISOLATE_FILE; + else + isolate_mode |= ISOLATE_ANON;
Above here, under "if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)", don't you need isolate_mode |= ISOLATE_ACTIVE | ISOLATE_FILE | ISOLATE_ANON; now to reproduce the same "all_lru_mode" behaviour as before? Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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@kvack.org"> email@kvack.org </a>