Commit 6c132b5f authored Sep 27, 2005 by John Stultz Committed by Linus Torvalds Sep 28, 2005

[PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs

This should resolve the issue seen in bugme bug #5105, where it is assumed
that dualcore x86_64 systems have synced TSCs.  This is not the case, and
alternate timesources should be used instead.

For more details, see:
http://bugzilla.kernel.org/show_bug.cgi?id=5105



Andi's earlier concerns that the TSCs should be synced on dualcore systems
have been resolved by confirmation from AMD folks that they can be
unsynced.

Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent a9d014af

arch/x86_64/kernel/time.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -959,9 +959,6 @@ static __init int unsynchronized_tsc(void)
		are handled in the OEM check above. */
		if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
		return 0;
		/* All in a single socket - should be synchronized */
		if (cpus_weight(cpu_core_map[0]) == num_online_cpus())
		return 0;
		#endif
		/* Assume multi socket systems are not synchronized */
		return num_online_cpus() > 1;