From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753235Ab0JHFyf (ORCPT ); Fri, 8 Oct 2010 01:54:35 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:55615 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752503Ab0JHFye (ORCPT ); Fri, 8 Oct 2010 01:54:34 -0400 Message-ID: <4CAEB1BA.2030604@kernel.org> Date: Thu, 07 Oct 2010 22:52:58 -0700 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100714 SUSE/3.0.6 Thunderbird/3.0.6 MIME-Version: 1.0 To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, yakui.zhao@intel.com, tglx@linutronix.de CC: linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/setup] x86, setup: Use string copy operation to optimze copy in kernel compression References: <1286502453-7043-1-git-send-email-yakui.zhao@intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/2010 10:40 PM, tip-bot for Zhao Yakui wrote: > Commit-ID: 68f4d5a00adaab33b136fce2c72d5c377b39b0b0 > Gitweb: http://git.kernel.org/tip/68f4d5a00adaab33b136fce2c72d5c377b39b0b0 > Author: Zhao Yakui > AuthorDate: Fri, 8 Oct 2010 09:47:33 +0800 > Committer: H. Peter Anvin > CommitDate: Thu, 7 Oct 2010 21:23:09 -0700 > > x86, setup: Use string copy operation to optimze copy in kernel compression > > The kernel decompression code parses the ELF header and then copies > the segment to the corresponding destination. Currently it uses slow > byte-copy code. This patch makes it use the string copy operations > instead. > > In the test the copy performance can be improved very significantly after using > the string copy operation mechanism. > 1. The copy time can be reduced from 150ms to 20ms on one Atom machine > 2. The copy time can be reduced about 80% on another machine > The time is reduced from 7ms to 1.5ms when using 32-bit kernel. > The time is reduced from 10ms to 2ms when using 64-bit kernel. > > Signed-off-by: Zhao Yakui > LKML-Reference: <1286502453-7043-1-git-send-email-yakui.zhao@intel.com> > Signed-off-by: H. Peter Anvin > --- > arch/x86/boot/compressed/misc.c | 29 +++++++++++++++++++++++------ > 1 files changed, 23 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c > index 8f7bef8..23f315c 100644 > --- a/arch/x86/boot/compressed/misc.c > +++ b/arch/x86/boot/compressed/misc.c > @@ -229,18 +229,35 @@ void *memset(void *s, int c, size_t n) > ss[i] = c; > return s; > } > - > +#ifdef CONFIG_X86_32 > void *memcpy(void *dest, const void *src, size_t n) > { > - int i; > - const char *s = src; > - char *d = dest; > + int d0, d1, d2; > + asm volatile( > + "rep ; movsl\n\t" > + "movl %4,%%ecx\n\t" > + "rep ; movsb\n\t" > + : "=&c" (d0), "=&D" (d1), "=&S" (d2) > + : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src) > + : "memory"); > > - for (i = 0; i < n; i++) > - d[i] = s[i]; > return dest; > } > +#else > +void *memcpy(void *dest, const void *src, size_t n) > +{ > + long d0, d1, d2; > + asm volatile( > + "rep ; movsq\n\t" > + "movq %4,%%rcx\n\t" > + "rep ; movsb\n\t" > + : "=&c" (d0), "=&D" (d1), "=&S" (d2) > + : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src) > + : "memory"); > > + return dest; > +} > +#endif > > static void error(char *x) > { wonder if it would have problem with some old AMD K8 systems. in amd.c /* On C+ stepping K8 rep microcode works well for copy/memset */ if (c->x86 == 0xf) { u32 level; level = cpuid_eax(1); if ((level >= 0x0f48 && level < 0x0f50) || level >= 0x0f58) set_cpu_cap(c, X86_FEATURE_REP_GOOD); ... } if (c->x86 >= 0x10) set_cpu_cap(c, X86_FEATURE_REP_GOOD); Yinghai