The patch titled
Subject: z3fold: discourage use of pages that weren't compacted
has been added to the -mm tree. Its filename is
z3fold-discourage-use-of-pages-that-werent-compacted.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/z3fold-discourage-use-of-pages-that-werent-compacted.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/z3fold-discourage-use-of-pages-that-werent-compacted.patch
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From: Vitaly Wool <vitalywool@xxxxxxxxx>
Subject: z3fold: discourage use of pages that weren't compacted
If a z3fold page couldn't be compacted, we don't want it to be used for
next object allocation in the first place. It makes more sense to add it
to the end of the relevant unbuddied list. If that page gets compacted
later, it will be added to the beginning of the list then.
This simple idea gives 5-7% improvement in randrw fio tests and about 10%
improvement in fio sequential read/write.
Link: http://lkml.kernel.org/r/20161115170038.75e127739b66f850e50d7fc1@xxxxxxxxx
Signed-off-by: Vitaly Wool <vitalywool@xxxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff -puN mm/z3fold.c~z3fold-discourage-use-of-pages-that-werent-compacted mm/z3fold.c
--- a/mm/z3fold.c~z3fold-discourage-use-of-pages-that-werent-compacted
+++ a/mm/z3fold.c
@@ -539,11 +539,19 @@ static void z3fold_free(struct z3fold_po
free_z3fold_page(zhdr);
atomic64_dec(&pool->pages_nr);
} else {
- z3fold_compact_page(zhdr);
+ int compacted = z3fold_compact_page(zhdr);
/* Add to the unbuddied list */
spin_lock(&pool->lock);
freechunks = num_free_chunks(zhdr);
- list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+ /*
+ * If the page has been compacted, we want to use it
+ * in the first place.
+ */
+ if (compacted)
+ list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+ else
+ list_add_tail(&zhdr->buddy,
+ &pool->unbuddied[freechunks]);
spin_unlock(&pool->lock);
z3fold_page_unlock(zhdr);
}
@@ -672,12 +680,16 @@ next:
spin_lock(&pool->lock);
list_add(&zhdr->buddy, &pool->buddied);
} else {
- z3fold_compact_page(zhdr);
+ int compacted = z3fold_compact_page(zhdr);
/* add to unbuddied list */
spin_lock(&pool->lock);
freechunks = num_free_chunks(zhdr);
- list_add(&zhdr->buddy,
- &pool->unbuddied[freechunks]);
+ if (compacted)
+ list_add(&zhdr->buddy,
+ &pool->unbuddied[freechunks]);
+ else
+ list_add_tail(&zhdr->buddy,
+ &pool->unbuddied[freechunks]);
}
}
_
Patches currently in -mm which might be from vitalywool@xxxxxxxxx are
z3fold-make-pages_nr-atomic.patch
z3fold-extend-compaction-function.patch
z3fold-use-per-page-spinlock.patch
z3fold-dont-fail-kernel-build-if-z3fold_header-is-too-big.patch
z3fold-discourage-use-of-pages-that-werent-compacted.patch
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