From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH 2/3] [CRYPTO] Add optimized SHA-1 implementation for i486+ Date: Sat, 09 Jun 2007 16:23:27 -0400 Message-ID: <466B0C3F.3040300@garzik.org> References: <20070608214242.23949.30350.stgit@dev> <20070608214253.23949.40465.stgit@dev> <20070609201159.GC11166@waste.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Benjamin Gilbert , akpm@linux-foundation.org, herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org To: Matt Mackall Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:34672 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759347AbXFIUXk (ORCPT ); Sat, 9 Jun 2007 16:23:40 -0400 In-Reply-To: <20070609201159.GC11166@waste.org> Sender: linux-crypto-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Matt Mackall wrote: > On Fri, Jun 08, 2007 at 05:42:53PM -0400, Benjamin Gilbert wrote: >> Add x86-optimized implementation of the SHA-1 hash function, taken from >> Nettle under the LGPL. This code will be enabled on kernels compiled for >> 486es or better; kernels which support 386es will use the generic >> implementation (since we need BSWAP). >> >> We disable building lib/sha1.o when an optimized implementation is >> available, as the library link order for x86 (and x86_64) would otherwise >> ignore the optimized version. The existing optimized implementation for ARM >> does not do this; the library link order for that architecture appears to >> favor the arch/arm/ version automatically. I've left this situation alone >> since I'm not familiar with the ARM code, but a !ARM condition could be >> added to CONFIG_SHA1_GENERIC if it makes sense. >> >> The code has been tested with tcrypt and the NIST test vectors. > > Have you benchmarked this against lib/sha1.c? Please post the results. > Until then, I'm frankly skeptical that your unrolled version is faster > because when I introduced lib/sha1.c the rolled version therein won by > a significant margin and had 1/10th the cache footprint. Yes. And it also depends on the CPU as well. Testing on a server-class x86 CPU (often with bigger L2, and perhaps even L1, cache) will produce different result than from popular but less-capable "value" CPUs. Jeff