The patch titled
Subject: mm/z3fold.c: improve compression by extending search
has been added to the -mm tree. Its filename is
z3fold-improve-compression-by-extending-search.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/z3fold-improve-compression-by-extending-search.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/z3fold-improve-compression-by-extending-search.patch
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------------------------------------------------------
From: Vitaly Wool <vitalywool@xxxxxxxxx>
Subject: mm/z3fold.c: improve compression by extending search
The current z3fold implementation only searches this CPU's page lists for
a fitting page to put a new object into. This patch adds quick search for
very well fitting pages (i. e. those having exactly the required number
of free space) on other CPUs too, before allocating a new page for that
object.
Link: http://lkml.kernel.org/r/20190417103733.72ae81abe1552397c95a008e@xxxxxxxxx
Signed-off-by: Vitaly Wool <vitaly.vul@xxxxxxxx>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@xxxxxxxxxxxxxx>
Cc: Uladzislau Rezki <urezki@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
--- a/mm/z3fold.c~z3fold-improve-compression-by-extending-search
+++ a/mm/z3fold.c
@@ -522,6 +522,42 @@ lookup:
}
put_cpu_ptr(pool->unbuddied);
+ if (!zhdr) {
+ int cpu;
+
+ /* look for _exact_ match on other cpus' lists */
+ for_each_online_cpu(cpu) {
+ struct list_head *l;
+
+ unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
+ spin_lock(&pool->lock);
+ l = &unbuddied[chunks];
+
+ zhdr = list_first_entry_or_null(READ_ONCE(l),
+ struct z3fold_header, buddy);
+
+ if (!zhdr || !z3fold_page_trylock(zhdr)) {
+ spin_unlock(&pool->lock);
+ zhdr = NULL;
+ continue;
+ }
+ list_del_init(&zhdr->buddy);
+ zhdr->cpu = -1;
+ spin_unlock(&pool->lock);
+
+ page = virt_to_page(zhdr);
+ if (test_bit(NEEDS_COMPACTING, &page->private)) {
+ z3fold_page_unlock(zhdr);
+ zhdr = NULL;
+ if (can_sleep)
+ cond_resched();
+ continue;
+ }
+ kref_get(&zhdr->refcount);
+ break;
+ }
+ }
+
return zhdr;
}
_
Patches currently in -mm which might be from vitalywool@xxxxxxxxx are
z3fold-introduce-helper-functions.patch
z3fold-improve-compression-by-extending-search.patch
z3fold-add-structure-for-buddy-handles.patch
z3fold-support-page-migration.patch
