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Message-ID: <c1a85d7d-d372-6d8f-5bd1-8e124c335d6a@gmail.com> Date: Thu, 11 Apr 2019 17:35:47 +0200 From: Vitaly Wool <vitalywool@...il.com> To: Linux-MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org Cc: Andrew Morton <akpm@...ux-foundation.org>, Oleksiy.Avramchenko@...y.com, Dan Streetman <ddstreet@...e.org> Subject: [PATCH 2/4] z3fold: 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. Signed-off-by: Vitaly Wool <vitaly.vul@...y.com> --- mm/z3fold.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/mm/z3fold.c b/mm/z3fold.c index 7a59875d880c..29a4f1249bef 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -522,6 +522,42 @@ static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool, } 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; } -- 2.17.1
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