Date: Sun, 26 Oct 2003 12:13:37 +0100 From: des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=) To: Peter Wemm <peter@wemm.org> Cc: cvs-src@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/i386 pmap.c Message-ID: <xzp3cdgb6am.fsf@dwp.des.no> In-Reply-To: <20031026064145.18F0E2A8D5@canning.wemm.org> (Peter Wemm's message of "Sat, 25 Oct 2003 23:41:45 -0700") References: <20031026064145.18F0E2A8D5@canning.wemm.org>
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Peter Wemm <peter@wemm.org> writes: > Massively deep pipelines help get the MHz up, and careful optimization can > stop it affecting frame rates. But it blows chunks if you mispredict a > branch in typical gcc generated code. Or take our libc syscall stubs.. > every single one will be mispredicted because the usual case (no errors) > has an opposite direction branch to what intel's static branch prediction > expects. Is there any way to teach (or trick) gcc to generate a branch which the p4 will predict correctly? DES --=20 Dag-Erling Sm=F8rgrav - des@des.no
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