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Date: Fri, 27 Aug 2010 11:02:52 +0900
Message-ID: <AANLkTin0PZu=ceoeyYa6qSv_piHL1yrfyEgTw35=gnex@mail.gmail.com>
Subject: Re: [RFC PATCH 0/3] Do not wait the full timeout on congestion_wait
 when there is no congestion
From: Minchan Kim <minchan.kim@gmail.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>, "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Rik van Riel <riel@redhat.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        "Li, Shaohua" <shaohua.li@intel.com>
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On Fri, Aug 27, 2010 at 10:50 AM, Wu Fengguang <fengguang.wu@intel.com> wrote:
> On Fri, Aug 27, 2010 at 09:41:48AM +0800, Minchan Kim wrote:
>> Hi, Wu.
>>
>> On Fri, Aug 27, 2010 at 10:21 AM, Wu Fengguang <fengguang.wu@intel.com> wrote:
>> > Minchan,
>> >
>> > It's much cleaner to keep the unchanged congestion_wait() and add a
>> > congestion_wait_check() for converting problematic wait sites. The
>> > too_many_isolated() wait is merely a protective mechanism, I won't
>> > bother to improve it at the cost of more code.
>>
>> You means following as?
>
> No, I mean do not change the too_many_isolated() related code at all :)
> And to use congestion_wait_check() in other places that we can prove
> there is a problem that can be rightly fixed by changing to
> congestion_wait_check().

I always suffer from understanding your comment.
Apparently, my eyes have a problem. ;(

This patch is dependent of Mel's series.
With changing congestion_wait with just return when no congestion, it
would have CPU hogging in too_many_isolated. I think it would apply in
Li's congestion_wait_check, too.
If no change is current congestion_wait, we doesn't need this patch.

Still, maybe I can't understand your comment. Sorry.
-- 
Kind regards,
Minchan Kim
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