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Date: Wed, 30 Nov 2016 12:02:33 +0100
From: Simon Horman <horms@verge.net.au>
Subject: Re: [PATCH] purgatory: Change default sha256 optimization to -O2
Message-ID: <20161130110233.GA31616@verge.net.au>
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To: Pratyush Anand <panand@redhat.com>
Cc: Geoff Levand <geoff@infradead.org>, Kexec Mailing List <kexec@lists.infradead.org>

On Mon, Nov 28, 2016 at 11:14:38AM +0530, Pratyush Anand wrote:
> On Thu, Nov 24, 2016 at 1:23 PM, Simon Horman <horms@verge.net.au> wrote:
> > On Wed, Nov 23, 2016 at 09:57:09AM -0800, Geoff Levand wrote:
> >> Change the default purgatory sha256 code optimization from -O0 to -O2, and add a
> >> new arch specific makefile variable $(ARCH)_PURGATORY_SHA256_CFLAGS which can
> >> over ride this default.  Set ia64_PURGATORY_SHA256_CFLAGS to -O0 to retain the
> >> previous optimization level for ia64.
> >>
> >> The purgatory sha256 code needs the be built with -O0 for the  ia64
> >> architecture.  Currently this code is built with -O0 for all architectures,
> >> which slows down the calculations for architectures which could otherwise
> >> use -O2.
> >
> > Could you give an indication of the performance improvement you expect,
> > e.g. on arm64?
> >
> 
> It takes around 20 second to verify SHA in purgatory when vmlinuz
> image is around 13MB and initramfs is around 30M with -O2 enables.
> Otherwise, it takes more than 2 minutes.

Thanks.

This patch doesn't seem to apply against the master branch.
I'm wondering if you or Geoff could:

1. Rebase the patch
2. Include some text about the performance improvement.
   Something like what is above would be fine from my pov.

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