From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f53.google.com (mail-la0-f53.google.com [209.85.215.53]) by kanga.kvack.org (Postfix) with ESMTP id 906CB6B006E for ; Thu, 20 Nov 2014 22:22:41 -0500 (EST) Received: by mail-la0-f53.google.com with SMTP id gm9so578639lab.26 for ; Thu, 20 Nov 2014 19:22:40 -0800 (PST) Received: from mail-lb0-x22f.google.com (mail-lb0-x22f.google.com. [2a00:1450:4010:c04::22f]) by mx.google.com with ESMTPS id p7si3644695lah.114.2014.11.20.19.22.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 20 Nov 2014 19:22:40 -0800 (PST) Received: by mail-lb0-f175.google.com with SMTP id u10so453666lbd.20 for ; Thu, 20 Nov 2014 19:22:40 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1416488913-9691-1-git-send-email-opensource.ganesh@gmail.com> References: <1416488913-9691-1-git-send-email-opensource.ganesh@gmail.com> From: Dan Streetman Date: Thu, 20 Nov 2014 22:22:19 -0500 Message-ID: Subject: Re: [PATCH] mm/zsmalloc: avoid duplicate assignment of prev_class Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Mahendran Ganesh Cc: Minchan Kim , Nitin Gupta , Joonsoo Kim , Linux-MM , linux-kernel On Thu, Nov 20, 2014 at 8:08 AM, Mahendran Ganesh wrote: > In zs_create_pool(), prev_class is assigned (ZS_SIZE_CLASSES - 1) > times. And the prev_class only references to the previous alloc > size_class. So we do not need unnecessary assignement. > > This patch modifies *prev_class* to *prev_alloc_class*. And the > *prev_alloc_class* will only be assigned when a new size_class > structure is allocated. > > Signed-off-by: Mahendran Ganesh > --- > mm/zsmalloc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index b3b57ef..ac2b396 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -970,7 +970,7 @@ struct zs_pool *zs_create_pool(gfp_t flags) > int size; > int pages_per_zspage; > struct size_class *class; > - struct size_class *prev_class; > + struct size_class *uninitialized_var(prev_alloc_class); + struct size_class *prev_class = NULL; Use the fact it's unset below, so set it to NULL here > > size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; > if (size > ZS_MAX_ALLOC_SIZE) > @@ -987,9 +987,8 @@ struct zs_pool *zs_create_pool(gfp_t flags) > * previous size_class if possible. > */ > if (i < ZS_SIZE_CLASSES - 1) { > - prev_class = pool->size_class[i + 1]; > - if (can_merge(prev_class, size, pages_per_zspage)) { > - pool->size_class[i] = prev_class; > + if (can_merge(prev_alloc_class, size, pages_per_zspage)) { > + pool->size_class[i] = prev_alloc_class; simplify more, we can check if this is the first iteration by looking at prev_class, e.g.: if (prev_class) { if (can_merge(prev_class, size, pages_per_zspage)) { pool->size_class[i] = prev_class; > continue; > } > } > @@ -1003,6 +1002,8 @@ struct zs_pool *zs_create_pool(gfp_t flags) > class->pages_per_zspage = pages_per_zspage; > spin_lock_init(&class->lock); > pool->size_class[i] = class; > + > + prev_alloc_class = class; > } > > pool->flags = flags; > -- > 1.7.9.5 > > -- > 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 -- 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