Date: Tue, 29 Mar 2016 14:09:05 +0000 From: "Pokala, Ravi" <rpokala@panasas.com> To: Konstantin Belousov <kib@FreeBSD.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r297374 - head/sys/x86/x86 Message-ID: <D5A320F4-9241-4FFB-B3B0-82B295856EDF@panasas.com> In-Reply-To: <201603290844.u2T8ivrN030045@repo.freebsd.org> References: <201603290844.u2T8ivrN030045@repo.freebsd.org>
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Hi Kib, -----Original Message----- From: <owner-src-committers@freebsd.org> on behalf of Konstantin Belousov <kib@FreeBSD.org> Date: 2016-03-29, Tuesday at 01:44 To: <src-committers@freebsd.org>, <svn-src-all@freebsd.org>, <svn-src-head@freebsd.org> Subject: svn commit: r297374 - head/sys/x86/x86 >Author: kib >Date: Tue Mar 29 08:44:56 2016 >New Revision: 297374 >URL: https://svnweb.freebsd.org/changeset/base/297374 > >... > >+ KASSERT((cpu_feature & CPUID_TSC) != 0 && tsc_freq != 0, >+ ("TSC not initialized")); >+ r = rdtsc(); >+ for (r = 0; r < LOOPS; r++) { >+ (void)lapic_read_icr_lo(); >+ ia32_pause(); >+ } >+ r = rdtsc() - r; > >... Doesn't use of r as the loop index overwrite the initial value returned by rdtsc()? -Ravi
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