From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754933AbYCYL5c (ORCPT ); Tue, 25 Mar 2008 07:57:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753626AbYCYL5Z (ORCPT ); Tue, 25 Mar 2008 07:57:25 -0400 Received: from outbound-sin.frontbridge.com ([207.46.51.80]:32874 "EHLO outbound1-sin-R.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753278AbYCYL5Y (ORCPT ); Tue, 25 Mar 2008 07:57:24 -0400 X-BigFish: VP X-MS-Exchange-Organization-Antispam-Report: OrigIP: 139.95.251.11;Service: EHS X-WSS-ID: 0JYABUZ-03-J2W-01 Date: Tue, 25 Mar 2008 12:56:59 +0100 From: Joerg Roedel To: Andi Kleen Cc: andreas.herrmann3@amd.com, tglx@linutronix.de, mingo@elte.hu, linux-kernel@vger.kernel.org Subject: Re: [PATCH] [6/7] Split large page mapping for AMD TSEG Message-ID: <20080325115659.GM17986@amd.com> References: <20080312353.598285931@firstfloor.org> <20080312025332.B5DFC1B41D1@basil.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080312025332.B5DFC1B41D1@basil.firstfloor.org> User-Agent: mutt-ng/devel-r804 (Linux) X-OriginalArrivalTime: 25 Mar 2008 11:56:59.0926 (UTC) FILETIME=[55098360:01C88E6F] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 12, 2008 at 03:53:32AM +0100, Andi Kleen wrote: > > On AMD SMM protected memory is part of the address map, but handled > internally like an MTRR. That leads to large pages getting split > internally which has some performance implications. Check for the > AMD TSEG MSR and split the large page mapping on that area > explicitely if it is part of the direct mapping. > > There is also SMM ASEG, but it is in the first 1MB and already covered by > the earlier split first page patch. > > Idea for this came from an earlier patch by Andreas Herrmann > > On a RevF dual Socket Opteron system kernbench shows a clear > improvement from this: > (together with the earlier patches in this series, especially the > split first 2MB patch) > > [lower is better] > no split stddev split stddev delta > Elapsed Time 87.146 (0.727516) 84.296 (1.09098) -3.2% > User Time 274.537 (4.05226) 273.692 (3.34344) -0.3% > System Time 34.907 (0.42492) 34.508 (0.26832) -1.1% > Percent CPU 322.5 (38.3007) 326.5 (44.5128) +1.2% > > => About 3.2% improvement in elapsed time for kernbench. > > With GB pages on AMD Fam1h the impact of splitting is much higher of course, > since it would split two full GB pages (together with the first > 1MB split patch) instead of two 2MB pages. I could not benchmark > a clear difference in kernbench on gbpages, so I kept it disabled > for that case > > That was only limited benchmarking of course, so if someone > was interested in running more tests for the gbpages case > that could be revisited (contributions welcome) > > I didn't bother implementing this for 32bit because it is very > unlikely the 32bit lowmem mapping overlaps into the TSEG near 4GB > and the 2MB low split is already handled for both. > > Signed-off-by: Andi Kleen Acked-by: Joerg Roedel > --- > arch/x86/kernel/setup_64.c | 13 +++++++++++++ > include/asm-x86/msr-index.h | 1 + > 2 files changed, 14 insertions(+) > > Index: linux/arch/x86/kernel/setup_64.c > =================================================================== > --- linux.orig/arch/x86/kernel/setup_64.c > +++ linux/arch/x86/kernel/setup_64.c > @@ -721,6 +721,20 @@ static void __cpuinit init_amd(struct cp > > if (amd_apic_timer_broken()) > disable_apic_timer = 1; > + > + if (!direct_gbpages && > + c == &boot_cpu_data && c->x86 >= 0xf && c->x86 <= 0x11) { > + unsigned long tseg; > + > + /* > + * Split up direct mapping around the TSEG SMM area. > + * Don't do it for gbpages because there seems very little > + * benefit in doing so. > + */ > + if (!rdmsrl_safe(MSR_K8_TSEG_ADDR, &tseg) && > + (tseg >> PMD_SHIFT) < (end_pfn_map >> (PMD_SHIFT-PAGE_SHIFT))) > + set_memory_4k((unsigned long)__va(tseg), 1); > + } > } > > void __cpuinit detect_ht(struct cpuinfo_x86 *c) > Index: linux/include/asm-x86/msr-index.h > =================================================================== > --- linux.orig/include/asm-x86/msr-index.h > +++ linux/include/asm-x86/msr-index.h > @@ -109,6 +109,7 @@ > #define MSR_K8_SYSCFG 0xc0010010 > #define MSR_K8_HWCR 0xc0010015 > #define MSR_K8_ENABLE_C1E 0xc0010055 > +#define MSR_K8_TSEG_ADDR 0xc0010112 > #define K8_MTRRFIXRANGE_DRAM_ENABLE 0x00040000 /* MtrrFixDramEn bit */ > #define K8_MTRRFIXRANGE_DRAM_MODIFY 0x00080000 /* MtrrFixDramModEn bit */ > #define K8_MTRR_RDMEM_WRMEM_MASK 0x18181818 /* Mask: RdMem|WrMem */ > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- | AMD Saxony Limited Liability Company & Co. 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