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Date: Mon, 7 Sep 2015 19:18:23 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: SIMD_PARA_SHA256

On Mon, Sep 07, 2015 at 10:15:54AM -0500, JimF wrote:
> On 9/7/2015 4:39 AM, Solar Designer wrote:
> >APU-specific microarchitectures don't have XOP, but I might be wrong.
> 
> My laptop is listed as AMD A8-4500M APU with Radeon.....   It is a dual 
> core HT, but the HT seems to not work as well here as in other HT boxes. 
> However, it is XOP, and seems to be a pretty good XOP. It's only 1.9GH, 
> but for some things, it keeps up with the Haswell. If you factor in 
> 128bit vs 256 bit, they run pretty even, even on the hashes that scream 
> on the AVX2 box.

Cool!  Per this table:

https://en.wikipedia.org/wiki/List_of_AMD_accelerated_processing_unit_microprocessors#Comal:_.22Trinity.22_.282012.2C_32_nm.29

A8-4500M is based on the Piledriver microarchitecture, so it's not an
"APU-specific microarchitecture", but rather is an APU built upon a
desktop CPU microarchitecture.  I actually checked this table out before
replying to magnum's message and found that some APUs are built upon
desktop CPU microarchitectures (and do have XOP) while others use what
appear to be APU-specific microarchitectures (and lack XOP).

> I can back validate findings made on other XOP boxes.

Yes, please.  I think it will be similar to verifying on a desktop
Piledriver.  I am surprised that "HT" (actually, two cores/module)
doesn't work as well for you as it does on other boxes - it should work
very well in Piledriver.  Maybe you're bumping into TDP or something.

Your embedded GPU appears to be:

HD 7640G	256:16:8	496 MHz	base, 685 MHz turbo

A small GPU we have in "well" might be usable to emulate some APUs as
well (in fact, this was the intent) - it's 7750 with DDR3-1600 memory.
lspci lists it as "Cape Verde PRO [Radeon HD 7750 / R7 250E]", and per
the Wikipedia page above this might match A10-78xx, FX-7600P, FX-8800P
except that those support faster DDR3-2133 memory.

Alexander

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