Message-ID: <5249D26C.8020208@hp.com>
Date: Mon, 30 Sep 2013 15:35:08 -0400
From: Waiman Long <waiman.long@hp.com>
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To: Tim Chen <tim.c.chen@linux.intel.com>
CC: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rik van Riel <riel@redhat.com>,
        Peter Hurley <peter@hurleysoftware.com>,
        Davidlohr Bueso <davidlohr.bueso@hp.com>,
        Alex Shi <alex.shi@intel.com>, Andrea Arcangeli <aarcange@redhat.com>,
        Matthew R Wilcox <matthew.r.wilcox@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Michel Lespinasse <walken@google.com>,
        Andi Kleen <andi@firstfloor.org>,
        "Chandramouleeswaran, Aswin" <aswin@hp.com>,
        "Norton, Scott J" <scott.norton@hp.com>
Subject: Re: [PATCH, v2] anon_vmas: Convert the rwsem to an rwlock_t
References: <1380308424-31011-1-git-send-email-Waiman.Long@hp.com>  <CA+55aFxXeQ69B1bfrO+0QtBqm0gt688LOshx=ppNjch10JF8FQ@mail.gmail.com>  <20130928074144.GA17773@gmail.com>  <CA+55aFyx-Lpqd8i2tHvhXCqL+nJZPq-6SikEkb-cQZEU9ogRjA@mail.gmail.com>  <20130928192123.GA8228@gmail.com> <20130928193739.GA8642@gmail.com>  <CA+55aFyMXxH-PGewqxse=VJzMdHWkyN4iKMh-VgQ1X2yJFnAgw@mail.gmail.com>  <20130928195207.GA31245@gmail.com> <1380561027.3467.196.camel@schen9-DESK>  <20130930181411.GO15690@laptop.programming.kicks-ass.net> <1380568987.3467.198.camel@schen9-DESK>
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On 09/30/2013 03:23 PM, Tim Chen wrote:
> On Mon, 2013-09-30 at 20:14 +0200, Peter Zijlstra wrote:
>> On Mon, Sep 30, 2013 at 10:10:27AM -0700, Tim Chen wrote:
>>> Here's the exim workload data:
>>>
>>> rwsem improvment:
>>> Waimain's patch:        +2.0%
>>> Alex+Tim's patchset:    +4.8%
>>> Waiman+Alex+Tim:        +5.3%
>>>
>>> convert rwsem to rwlock_t for root anon_vma lock
>>> Ingo's patch		+11.7%
>>>
>> What happens if you stuff Waiman's qrwlock patches on top of that?
>> admittedly and oft mentioned in this thread, our current rwlock_t is
>> somewhat suboptimal under a number of conditions.
> I've tested with Waiman's qrwlock patches on top of Ingo's patches.
> It does not affect the throughput for exim and I still get
> about +11.7% throughput change (same as with Ingo's patch only).
>
> Tim
>

My qrwlock doesn't enable qrwlock by default. You have to use menuconfig 
to explicitly enable it. Have you done that when you build the test 
kernel? I am thinking of explicitly enabling it for x86 if the anon-vma 
lock is converted back to a rwlock.

-Longman
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