Date: Mon, 30 Sep 2013 20:14:11 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Waiman Long <Waiman.Long@hp.com>, 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
Message-ID: <20130930181411.GO15690@laptop.programming.kicks-ass.net>
References: <1380308424-31011-1-git-send-email-Waiman.Long@hp.com>
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 <20130928192123.GA8228@gmail.com>
 <20130928193739.GA8642@gmail.com>
 <CA+55aFyMXxH-PGewqxse=VJzMdHWkyN4iKMh-VgQ1X2yJFnAgw@mail.gmail.com>
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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.
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