Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753708AbaKXQ5S (ORCPT ); Mon, 24 Nov 2014 11:57:18 -0500 Received: from mail-ig0-f171.google.com ([209.85.213.171]:36045 "EHLO mail-ig0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750966AbaKXQ5Q (ORCPT ); Mon, 24 Nov 2014 11:57:16 -0500 MIME-Version: 1.0 In-Reply-To: <1416577403-7887-1-git-send-email-opensource.ganesh@gmail.com> References: <1416577403-7887-1-git-send-email-opensource.ganesh@gmail.com> From: Dan Streetman Date: Mon, 24 Nov 2014 11:56:55 -0500 X-Google-Sender-Auth: HJ0DV6Cnex1AUjrhoCtFgwqi1X4 Message-ID: Subject: Re: [PATCH v2] mm/zsmalloc: avoid duplicate assignment of prev_class To: Mahendran Ganesh Cc: Minchan Kim , Nitin Gupta , Joonsoo Kim , Linux-MM , linux-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 21, 2014 at 8:43 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 size_class. > So we do not need unnecessary assignement. > > This patch assigns *prev_class* when a new size_class structure > is allocated and uses prev_class to check whether the first class > has been allocated. > > Signed-off-by: Mahendran Ganesh > > --- > v1 -> v2: > - follow Dan Streetman's advise to use prev_class to > check whether the first class has been allocated > - follow Minchan Kim's advise to remove uninitialized_var() > --- > mm/zsmalloc.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index b3b57ef..810eda1 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 *prev_class = NULL; Maybe I'm looking at the wrong source tree, but I don't think this will work? You have to move prev_class outside the for loop, or it'll be NULL each iteration. > > size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; > if (size > ZS_MAX_ALLOC_SIZE) > @@ -986,8 +986,7 @@ struct zs_pool *zs_create_pool(gfp_t flags) > * characteristics. So, we makes size_class point to > * previous size_class if possible. > */ > - if (i < ZS_SIZE_CLASSES - 1) { > - prev_class = pool->size_class[i + 1]; > + 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_class = class; > } > > pool->flags = flags; > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/