linux-kernel - Re: [this_cpu_xx V4 00/20] Introduce per cpu atomic operations and avoid per cpu address arithmetic

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Message-ID: <20091002095455.GC21427@elte.hu>
Date:	Fri, 2 Oct 2009 11:54:55 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Tejun Heo <tj@...nel.org>
Cc:	cl@...ux-foundation.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, rusty@...tcorp.com.au,
	Pekka Enberg <penberg@...helsinki.fi>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [this_cpu_xx V4 00/20] Introduce per cpu atomic operations and
	avoid per cpu address arithmetic

* Tejun Heo <tj@...nel.org> wrote:

> Hello,
> 
> cl@...ux-foundation.org wrote:
> > V3->V4:
> > - Fix various macro definitions.
> > - Provider experimental percpu based fastpath that does not disable
> >   interrupts for SLUB.
> 
> The series looks very good to me. [...]

Seconded, very nice series!

One final step/cleanup seems to be missing from it: it should replace 
current uses of percpu_op() [percpu_read(), etc.] in the x86 tree and 
elsewhere with the new this_cpu_*() primitives. this_cpu_*() is using 
per_cpu_from_op/per_cpu_to_op directly, we dont need those percpu_op() 
variants anymore.

There should also be a kernel image size comparison done for that step, 
to make sure all the new primitives are optimized to the max on the 
instruction level.

> [...] percpu#for-next now has ia64 bits included and the legacy 
> allocator is gone there so it can carry this series.  Sans the last 
> one, they seem they can be stable and incremental from now on, right?  
> Shall I include this series into the percpu tree?

I'd definitely recommend doing that - it should be tested early and wide 
for v2.6.33, and together with other percpu bits.

	Ingo
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