[Mono-dev] SHA1Managed speedups

[Igor Guerrero]

Hi Sebastien,

Thanks for your help and suggestions... I read in the chats between Scott
and Alan about the performance gain using their SHA1 improvements, that it
was about 40%, obviously my eyes shined after reading that.

@hector we were doing SHA1 all wrong :(

On Tue, Apr 29, 2008 at 12:21 PM, Sebastien Pouliot <
sebastien.pouliot at gmail.com> wrote:

> Hello Hector,
>
> On Tue, 2008-04-29 at 10:42 -0500, Hector E. Gomez Morales wrote:
> > Hi all:
> >
> > I am working in the implementation of Git# with Igor Guerrero so we will
> > be intensive users of SHA1Managed
>
> Well you should no be - at least not with so many details ;-)
>
> The right way to access cryptography in .NET is to use the Create()
> (factory) methods from the base class that represent the algorithm, not
> the implementation.
>
>        I.e. you should not be using SHA1Managed (or
>        SHA1CryptoServiceProvider) but SHA1.Create()
>
> This allows the Mono (or .NET) runtime to select the right (default or
> user selected) implementation for any algorithms.
>
>        E.g. it would let someone change the default SHA1 to a native
>        (or hardware assisted) implementation without modifying any
>        application.
>
> Historical note: it also served (MS) as a workaround for a bug in
> SHA1CryptoServiceProvider (fx1.x) on multithreaded servers. They simply
> (for WSE 1.0) updated machine.config to use SHA1Managed instead. That
> fixed the problem for every application who followed the design
> correctly.
>
> > so we will like to help in anyway to help improve sha1 performance.
>
> Thanks!
>
> Ping/email me when you get ready to profile your code. We'll see how
> much impact SHA1 has and, if required, check a few options from there
> (but be sure to use SHA1.Create ;-)
>
> Sebastien
>
> p.s. yes it's been on my Gendarme todo list for quite some time :)
>
> > Hector
> >
> >
> > Sebastien Pouliot wrote:
> > > Great! :-)
> > >
> > > Sebastien
> > >
> > > p.s. there are quite a few other options possible (I mentioned Crimson
> > > before) within or outside Mono if you still need/want more performance
> > > out of SHA1.
> > >
> > > On Tue, 2008-04-29 at 14:36 +0100, Alan McGovern wrote:
> > >>>  Please remove the unsafe keyword from both methods.
> > >> Ah, sorry. I attached the wrong patch. Kangaroo had already pointed
> > >> out that i had left in the unsafe keyword as part of my copy/paste
> > >> from my working copy and i thought i recreated the patch when i fixed
> > >> that, but obviously not.
> > >>
> > >>>  Please always provide numbers (and the test cases) with performance
> > >>>  patches. Also compare the results with the code already in SVN (not
> the
> > >>>  previous releases) this way we compare the patch with the gain it
> > >>>  provides.
> > >> The 'Big Win' in this patch is unrolling the first loop. I'll attach
> > >> some numbers later giving exact details as to where the gains are as
> > >> compared to SVN head.
> > >>
> > >>>  He asked me, more than once, to consider re-rolling the
> > >>>  SHA1 code. This piece of code is often the largest one the JIT is
> likely
> > >>>  to compile, as since it's used for assembly names it's a
> performance
> > >>>  (JIT time) hit being transfered to most Mono applications.
> > >> If the JIT cost is prohibitive to making this patch acceptable, i can
> > >> test partial unrolling of all the loops. I should be able to cut the
> > >> codesize by a large proportion while still getting the majority of
> the
> > >> speed beneffits. I'll testbench that later too.
> > >>
> > >> Thanks,
> > >> Alan.
> > >
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> > >
> >
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-- 
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