Date: Sun, 23 Nov 2008 00:51:58 +0000 From: "Kip Macy" <kmacy@freebsd.org> To: "Scott Long" <scottl@samsco.org> Cc: Kostik Belousov <kostikbel@gmail.com>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r185162 - in head: . sys/amd64/include sys/arm/include sys/conf sys/dev/bce sys/dev/cxgb sys/dev/cxgb/sys sys/dev/cxgb/ulp/iw_cxgb sys/dev/mxge sys/dev/nxge sys/i386/include sys/i386/in... Message-ID: <3c1674c90811221651u338294frcdbd99b386733851@mail.gmail.com> In-Reply-To: <4928910B.1020403@samsco.org> References: <200811220555.mAM5tuIJ007781@svn.freebsd.org> <20081122112949.GA6408@deviant.kiev.zoral.com.ua> <3c1674c90811221326m41e229f7p6abbc0eb473e900e@mail.gmail.com> <49288222.5060205@samsco.org> <20081122221953.GO6408@deviant.kiev.zoral.com.ua> <4928910B.1020403@samsco.org>
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On Sat, Nov 22, 2008 at 11:08 PM, Scott Long <scottl@samsco.org> wrote: > Kostik Belousov wrote: >> >> On Sat, Nov 22, 2008 at 03:05:22PM -0700, Scott Long wrote: >>> >>> A neat hack would be for the kernel linker to scan the text and do a >>> drop-in replacement of the opcode that is appropriate for the platform. >>> I can't see how a CPU_XXX definition would work because it's just a >>> compile time construct, one that can be included with any kernel >>> compile. >> >> Yes, it is possible to do that. Less drastic change is to directly >> check features. I moved slow code to separate section to eliminate >> unconditional jump in fast path. >> Only compile-tested. >> > > As long as it works, I think it's a step in the right direction; I'm > assuming that cpu_feature is a symbol filled in at runtime and not a > macro for the cpuid instruction, right? > > Scott > i386/include/md_var.h: <..> extern u_int cpu_exthigh; extern u_int cpu_feature; extern u_int cpu_feature2; extern u_int amd_feature; extern u_int amd_feature2; <...> I'm not thrilled with it, but we can revisit the issue if it makes a measurable difference on someone's workload. Thanks, Kip -- If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis
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