From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753184AbaHMPWA (ORCPT ); Wed, 13 Aug 2014 11:22:00 -0400 Received: from relay.variantweb.net ([104.131.199.242]:53339 "EHLO relay.variantweb.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751518AbaHMPV6 (ORCPT ); Wed, 13 Aug 2014 11:21:58 -0400 Date: Wed, 13 Aug 2014 10:21:48 -0500 From: Seth Jennings To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Jerome Marchand , juno.choi@lge.com, seungho1.park@lge.com, Luigi Semenzato , Nitin Gupta Subject: Re: [RFC 1/3] zsmalloc: move pages_allocated to zs_pool Message-ID: <20140813152148.GA2768@cerebellum.variantweb.net> References: <1407225723-23754-1-git-send-email-minchan@kernel.org> <1407225723-23754-2-git-send-email-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1407225723-23754-2-git-send-email-minchan@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 05, 2014 at 05:02:01PM +0900, Minchan Kim wrote: > Pages_allocated has counted in size_class structure and when user > want to see total_size_bytes, it gathers all of value from each > size_class to report the sum. > > It's not bad if user don't see the value often but if user start > to see the value frequently, it would be not a good deal for > performance POV. > > This patch moves the variable from size_class to zs_pool so it would > reduce memory footprint (from [255 * 8byte] to [sizeof(atomic_t)]) > but it adds new locking overhead but it wouldn't be severe because > it's not a hot path in zs_malloc(ie, it is called only when new > zspage is created, not a object). > > Signed-off-by: Minchan Kim > --- > mm/zsmalloc.c | 30 ++++++++++++++++-------------- > 1 file changed, 16 insertions(+), 14 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index fe78189624cf..a6089bd26621 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -198,9 +198,6 @@ struct size_class { > > spinlock_t lock; > > - /* stats */ > - u64 pages_allocated; > - > struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS]; > }; > > @@ -216,9 +213,12 @@ struct link_free { > }; > > struct zs_pool { > + spinlock_t stat_lock; > + > struct size_class size_class[ZS_SIZE_CLASSES]; > > gfp_t flags; /* allocation flags used when growing pool */ > + unsigned long pages_allocated; As Dan was saying, I think this can be atomic to avoid the locking. Seth > }; > > /* > @@ -882,6 +882,7 @@ struct zs_pool *zs_create_pool(gfp_t flags) > > } > > + spin_lock_init(&pool->stat_lock); > pool->flags = flags; > > return pool; > @@ -943,8 +944,10 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) > return 0; > > set_zspage_mapping(first_page, class->index, ZS_EMPTY); > + spin_lock(&pool->stat_lock); > + pool->pages_allocated += class->pages_per_zspage; > + spin_unlock(&pool->stat_lock); > spin_lock(&class->lock); > - class->pages_allocated += class->pages_per_zspage; > } > > obj = (unsigned long)first_page->freelist; > @@ -997,14 +1000,14 @@ void zs_free(struct zs_pool *pool, unsigned long obj) > > first_page->inuse--; > fullness = fix_fullness_group(pool, first_page); > - > - if (fullness == ZS_EMPTY) > - class->pages_allocated -= class->pages_per_zspage; > - > spin_unlock(&class->lock); > > - if (fullness == ZS_EMPTY) > + if (fullness == ZS_EMPTY) { > + spin_lock(&pool->stat_lock); > + pool->pages_allocated -= class->pages_per_zspage; > + spin_unlock(&pool->stat_lock); > free_zspage(first_page); > + } > } > EXPORT_SYMBOL_GPL(zs_free); > > @@ -1100,12 +1103,11 @@ EXPORT_SYMBOL_GPL(zs_unmap_object); > > u64 zs_get_total_size_bytes(struct zs_pool *pool) > { > - int i; > - u64 npages = 0; > - > - for (i = 0; i < ZS_SIZE_CLASSES; i++) > - npages += pool->size_class[i].pages_allocated; > + u64 npages; > > + spin_lock(&pool->stat_lock); > + npages = pool->pages_allocated; > + spin_unlock(&pool->stat_lock); > return npages << PAGE_SHIFT; > } > EXPORT_SYMBOL_GPL(zs_get_total_size_bytes); > -- > 2.0.0 > > -- > 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/ . > Don't email: email@kvack.org