From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f52.google.com (mail-pa0-f52.google.com [209.85.220.52]) by kanga.kvack.org (Postfix) with ESMTP id 3F04B6B0035 for ; Thu, 29 May 2014 08:56:08 -0400 (EDT) Received: by mail-pa0-f52.google.com with SMTP id bj1so9203pad.25 for ; Thu, 29 May 2014 05:56:07 -0700 (PDT) Received: from mail-pb0-x22f.google.com (mail-pb0-x22f.google.com [2607:f8b0:400e:c01::22f]) by mx.google.com with ESMTPS id ns7si786616pbb.248.2014.05.29.05.56.07 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 29 May 2014 05:56:07 -0700 (PDT) Received: by mail-pb0-f47.google.com with SMTP id rp16so335915pbb.6 for ; Thu, 29 May 2014 05:56:07 -0700 (PDT) Message-ID: <1401368165.3645.21.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: [PATCH] vmalloc: use rcu list iterator to reduce vmap_area_lock contention From: Eric Dumazet Date: Thu, 29 May 2014 05:56:05 -0700 In-Reply-To: <1401344554-3596-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1401344554-3596-1-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , Zhang Yanfei , Johannes Weiner , Andi Kleen , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Richard Yao On Thu, 2014-05-29 at 15:22 +0900, Joonsoo Kim wrote: > Richard Yao reported a month ago that his system have a trouble > with vmap_area_lock contention during performance analysis > by /proc/meminfo. Andrew asked why his analysis checks /proc/meminfo > stressfully, but he didn't answer it. > > https://lkml.org/lkml/2014/4/10/416 > > Although I'm not sure that this is right usage or not, there is a solution > reducing vmap_area_lock contention with no side-effect. That is just > to use rcu list iterator in get_vmalloc_info(). This function only needs > values on vmap_area structure, so we don't need to grab a spinlock. > > Reported-by: Richard Yao > Signed-off-by: Joonsoo Kim Nice, I was considering the same Acked-by: Eric Dumazet -- 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