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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@gmail.com
Signed-off-by: Vitaly Wool <vitaly.vul@sony.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vitaly Wool 2019-05-13 17:22:46 -07:00 committed by Linus Torvalds
parent 9050cce104
commit 351618b203
1 changed files with 36 additions and 0 deletions
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36
mm/z3fold.c
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@ -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;
}