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Date: Tue, 14 Jul 2015 12:11:16 +0800
From: Lei Zhang <zhanglei.april@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: Interleaving of intrinsics
> On Jun 23, 2015, at 2:03 AM, Solar Designer <solar@...nwall.com> wrote:
>
> One thing that is clear is that non-fully-unrolled *_PARA_DO are not
> acceptable. If there are not enough registers for fully unrolling
> these without incurring spilling, then the interleaving factor should be
> smaller. On MIC, there should be enough registers for the interleaving
> factors considered above (up to 5x).
I just manually unrolled SHA256_STEP and SHA512_STEP respectively, and compared the performance with the auto-unrolled ones, using magnum's testpara.pl. The figures below are obtained on my laptop (formats are pbkdf2-*):
[auto]
hash\para | 1 | 2 | 3 | 4 | 5 |
-----------|----------|----------|----------|----------|----------|
sha256 | **4020**| 3760 | 3924 | 3801 | 3940 |
sha512 | **1624**| 1092 | 1413 | 1409 | 1435 |
[manual]
hash\para | 1 | 2 | 3 | 4 | 5 |
-----------|----------|----------|----------|----------|----------|
sha256 | **4144**| 1888 | 1817 | 1837 | 1821 |
sha512 | **1646**| 748 | 708 | 720 | 722 |
With manual unrolling, the performance degrades drastically from interleaving x1 to x2, but not so much upwards. BTW, I didn't change the original array tmps. Just the loop is manually unrolled here.
Lei
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