Date: Sun, 11 May 2014 16:48:36 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r265882 - in stable/9/sys/cddl/dev/dtrace: amd64 i386 Message-ID: <201405111648.s4BGmaPx071012@svn.freebsd.org>
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Author: markj Date: Sun May 11 16:48:36 2014 New Revision: 265882 URL: http://svnweb.freebsd.org/changeset/base/265882 Log: MFC r236566 (by zml): Fix DTrace TSC skew calculation: The skew calculation here is exactly backwards. We were able to repro it on a multi-package ESX server running a FreeBSD VM, where the TSCs can be pretty evil. Modified: stable/9/sys/cddl/dev/dtrace/amd64/dtrace_subr.c stable/9/sys/cddl/dev/dtrace/i386/dtrace_subr.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/cddl/dev/dtrace/amd64/dtrace_subr.c ============================================================================== --- stable/9/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Sun May 11 16:34:17 2014 (r265881) +++ stable/9/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Sun May 11 16:48:36 2014 (r265882) @@ -445,7 +445,7 @@ dtrace_gethrtime() * (see nsec_scale calculations) taking into account 32-bit shift of * the higher half and finally add. */ - tsc = rdtsc() + tsc_skew[curcpu]; + tsc = rdtsc() - tsc_skew[curcpu]; lo = tsc; hi = tsc >> 32; return (((lo * nsec_scale) >> SCALE_SHIFT) + Modified: stable/9/sys/cddl/dev/dtrace/i386/dtrace_subr.c ============================================================================== --- stable/9/sys/cddl/dev/dtrace/i386/dtrace_subr.c Sun May 11 16:34:17 2014 (r265881) +++ stable/9/sys/cddl/dev/dtrace/i386/dtrace_subr.c Sun May 11 16:48:36 2014 (r265882) @@ -454,7 +454,7 @@ dtrace_gethrtime() * (see nsec_scale calculations) taking into account 32-bit shift of * the higher half and finally add. */ - tsc = rdtsc() + tsc_skew[curcpu]; + tsc = rdtsc() - tsc_skew[curcpu]; lo = tsc; hi = tsc >> 32; return (((lo * nsec_scale) >> SCALE_SHIFT) +
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