Return-Path: thread-index: AcQVpHAVHd7uB24STWeB5j6SbV8ciA== Envelope-to: paul@sumlocktest.fsnet.co.uk Delivery-date: Sun, 04 Jan 2004 12:30:06 +0000 Message-ID: <01ca01c415a4$70159920$d100000a@sbs2003.local> X-Mailer: Microsoft CDO for Exchange 2000 Content-Class: urn:content-classes:message Importance: normal Priority: normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.0 Date: Mon, 29 Mar 2004 16:42:27 +0100 From: "Mikael Pettersson" To: Subject: Re: Pentium M config option for 2.6 Cc: , Sender: X-Mailing-List: linux-kernel@vger.kernel.org X-OriginalArrivalTime: 29 Mar 2004 15:42:29.0906 (UTC) FILETIME=[71AADF20:01C415A4] On Sun, 4 Jan 2004 03:28:48 +0100, Tomas Szepe wrote: >Since the Pentium M has 64 byte cache lines and is not a K7 or K8... ;) ... >--- a/arch/i386/Makefile 2003-09-28 11:38:05.000000000 +0200 >+++ b/arch/i386/Makefile 2004-01-04 03:02:52.000000000 +0100 >@@ -35,6 +35,7 @@ > cflags-$(CONFIG_MPENTIUMII) += $(call check_gcc,-march=pentium2,-march=i686) > cflags-$(CONFIG_MPENTIUMIII) += $(call check_gcc,-march=pentium3,-march=i686) > cflags-$(CONFIG_MPENTIUM4) += $(call check_gcc,-march=pentium4,-march=i686) >+cflags-$(CONFIG_MPENTIUMM) += $(call check_gcc,-march=pentium4,-march=i686) > cflags-$(CONFIG_MK6) += $(call check_gcc,-march=k6,-march=i586) > # Please note, that patches that add -march=athlon-xp and friends are pointless. > # They make zero difference whatsosever to performance at this time. P-M is not a P4 core, it's an enhanced PIII core. SSE2 was added, but compiler support for SSE2 f.p. math shouldn't matter for the kernel. Using P4 optimisations on a P-M may actually reduce performance, due to the different micro-architectures. (P4 made shifts and some leas more expensive, and simple add/and/sub/etc less expensive.) IOW, don't lie to the compiler and pretend P-M == P4 with that -march=pentium4. And since P-M doesn't do SMP, does cache line size even matter? There are no locks to protect from ping-ponging. /Mikael - 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/