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Re: [PATCH] MIPS: Make collection of FPU emulator statistics optional.

To: Thomas Bogendoerfer <>
Subject: Re: [PATCH] MIPS: Make collection of FPU emulator statistics optional.
From: Ralf Baechle <>
Date: Tue, 3 Nov 2009 11:21:12 +0100
Cc: David Daney <>,
In-reply-to: <>
Original-recipient: rfc822;
References: <> <> <>
User-agent: Mutt/1.5.19 (2009-01-05)
On Tue, Nov 03, 2009 at 10:37:43AM +0100, Ralf Baechle wrote:

> > On Mon, Nov 02, 2009 at 04:12:35PM -0800, David Daney wrote:
> > > On SMP systems, the collection of statistics can cause cache line
> > > bouncing in the lines associated with the counters.  Make the
> > > statistics configurable so this can be avoided.  Also we need to make
> > > the counters atomic_t so that they can be reliably modified on SMP
> > > systems.
> > 
> > how about making it a per_cpu thing and avoid the atomic instructions ?
> Working on that.  The tricky part is that statistics may end up somewhat
> inaccurate when a reader iterates over the per-CPU array of stats to add
> them all up.  I've not found a solution for that yet but then again it
> should not be something which actually would cause pain.

Or more useful than a global statistics would be per process stats.

How should a useful interface look like?


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