linux-kernel - Re: x86 memcpy performance

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 16 Aug 2011 09:43:10 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	melwyn lobo <linux.melwyn@...il.com>
Cc:	Denys Vlasenko <vda.linux@...glemail.com>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	borislav.petkov@....com
Subject: Re: x86 memcpy performance

On Tue, Aug 16, 2011 at 12:49:28PM +0530, melwyn lobo wrote:
> We would rather use the 32 bit patch. Have you already got a 32 bit
> patch.

Nope, only 64-bit for now, sorry.

> How can I use sse3 for 32 bit.

Well, OTTOMH, you have only 8 xmm regs in 32-bit instead of 16, which
should halve the performance of the 64-bit version in a perfect world.
However, we don't know how the performance of a 32-bit SSE memcpy
version behaves vs the gcc builtin one - that would require benchmarking
too.

But other than that, I don't see a problem with having a 32-bit version.

> I don't think you have submitted 64 bit patch in the mainline.
> Is there still work ongoing on this.

Yeah, we are currently benchmarking it to see whether it actually makes
sense to even have SSE memcpy in the kernel.

-- 
Regards/Gruss,
    Boris.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/