diff options
| author |   Andi Kleen <ak@suse.de> | 2006-01-11 22:45:15 +0100 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-11 19:04:57 -0800 |
| commit | 737c5c3bde5641af9c24e3a60366674af72a43ef (patch) | |
| tree | e369c6489279c9fda4a5fb1766fe1966ce9caf87 /arch/x86_64/kernel/smpboot.c | |
| parent | [PATCH] x86_64: Fix compile error with !CONFIG_COMPAT (diff) | |
| download | linux-dev-737c5c3bde5641af9c24e3a60366674af72a43ef.tar.xz linux-dev-737c5c3bde5641af9c24e3a60366674af72a43ef.zip | |
[PATCH] x86_64: Don't try to synchronize the TSC over CPUs on Intel CPUs at boot.
They already do this in hardware and the Linux algorithm
actually adds errors.
Cc: mingo@elte.hu
Cc: rohit.seth@intel.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/x86_64/kernel/smpboot.c')
| -rw-r--r-- | arch/x86_64/kernel/smpboot.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c index e6af93b51dce..994728564d6b 100644 --- a/arch/x86_64/kernel/smpboot.c +++ b/arch/x86_64/kernel/smpboot.c @@ -335,7 +335,13 @@ static __cpuinit void sync_tsc(unsigned int master) static void __cpuinit tsc_sync_wait(void) { - if (notscsync || !cpu_has_tsc) + /* + * When the CPU has synchronized TSCs assume the BIOS + * or the hardware already synced. Otherwise we could + * mess up a possible perfect synchronization with a + * not-quite-perfect algorithm. + */ + if (notscsync || !cpu_has_tsc || !unsynchronized_tsc()) return; sync_tsc(0); } |