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Re: [PATCH v2 01/25] powerpc/8xx: Save r3 all the time in DTLB miss handler

From Scott Wood <scottwood@freescale.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 01/25] powerpc/8xx: Save r3 all the time in DTLB miss handler
Date 2015-09-29 00:10 +0200
Message-ID <qdOMq-43G-5@gated-at.bofh.it> (permalink)
References <qbz57-2KT-3@gated-at.bofh.it> <qbzeN-3bq-21@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tue, Sep 22, 2015 at 06:50:29PM +0200, Christophe Leroy wrote:
> We are spending between 40 and 160 cycles with a mean of 65 cycles in
> the TLB handling routines (measured with mftbl) so make it more
> simple althought it adds one instruction.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Does this just make it simpler or does it make it faster?  What is the
performance impact?  Is the performance impact seen with or without
CONFIG_8xx_CPU6 enabled?  Without it, it looks like you're adding an
mtspr/mfspr combo in order to replace one mfspr.

-Scott
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[PATCH v2 01/25] powerpc/8xx: Save r3 all the time in DTLB miss  handler Christophe Leroy <christophe.leroy@c-s.fr> - 2015-09-22 19:10 +0200
  Re: [PATCH v2 01/25] powerpc/8xx: Save r3 all the time in DTLB miss  handler Scott Wood <scottwood@freescale.com> - 2015-09-29 00:10 +0200

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