Date: Tue, 12 Apr 2011 22:41:53 +0000 (UTC) From: Jung-uk Kim <jkim@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r220581 - head/sys/x86/isa Message-ID: <201104122241.p3CMfrhY037768@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: jkim Date: Tue Apr 12 22:41:52 2011 New Revision: 220581 URL: http://svn.freebsd.org/changeset/base/220581 Log: Do not use TSC for DELAY(9) if it not P-state invariant to avoid possible foot-shooting. DELAY() becomes unreliable when TSC frequency varies wildly, especially cpufreq(4) and powerd(8) are used at the same time. Modified: head/sys/x86/isa/clock.c Modified: head/sys/x86/isa/clock.c ============================================================================== --- head/sys/x86/isa/clock.c Tue Apr 12 22:22:01 2011 (r220580) +++ head/sys/x86/isa/clock.c Tue Apr 12 22:41:52 2011 (r220581) @@ -263,7 +263,7 @@ delay_tc(int n) tc = timecounter; freq = atomic_load_acq_64(&tsc_freq); - if (freq != 0) { + if (tsc_is_invariant && freq != 0) { func = get_tsc; mask = ~0u; } else {
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201104122241.p3CMfrhY037768>