From b2468e525f29882f866cb0b832956e69328f9647 Mon Sep 17 00:00:00 2001 From: Jan Beulich <jbeulich@novell.com> Date: Tue, 30 May 2006 22:47:54 +0200 Subject: [PATCH] [PATCH] x86_64: fix last_tsc calculation of PM timer From: "Jan Beulich" <jbeulich@novell.com> The PM timer code updates vxtime.last_tsc, but this update was done incorrectly in two ways: - offset_delay being in microseconds requires multiplying with cpu_mhz rather than cpu_khz - the multiplication of offset_delay and cpu_khz (both being 32-bit values) on most current CPUs would overflow (observed value of the delay was approximately 4000us, yielding an overflow for frequencies starting a little above 1GHz) Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org> --- arch/x86_64/kernel/pmtimer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86_64/kernel/pmtimer.c b/arch/x86_64/kernel/pmtimer.c index b0444a415bd6..bf421ed26808 100644 --- a/arch/x86_64/kernel/pmtimer.c +++ b/arch/x86_64/kernel/pmtimer.c @@ -68,7 +68,7 @@ int pmtimer_mark_offset(void) offset_delay = delta % (USEC_PER_SEC / HZ); rdtscll(tsc); - vxtime.last_tsc = tsc - offset_delay * cpu_khz; + vxtime.last_tsc = tsc - offset_delay * (u64)cpu_khz / 1000; /* don't calculate delay for first run, or if we've got less then a tick */ -- GitLab