Subject: Re: [PATCH, v2] anon_vmas: Convert the rwsem to an rwlock_t
From: Tim Chen <tim.c.chen@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
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>
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Date: Mon, 30 Sep 2013 12:23:07 -0700
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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

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