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| author | Andi Kleen <ak@suse.de> | 2005-10-13 14:41:44 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2005-10-13 14:41:44 -0700 |
| commit | 34cb711ba922f53cca45443b8c3c1078873cf599 (patch) | |
| tree | 2b120d59460047caff9546d68f445626947d47fc /net/sched | |
| parent | c8923c6b852d3a97c1faad0566e38fca330375a7 (diff) | |
| download | lwn-34cb711ba922f53cca45443b8c3c1078873cf599.tar.gz lwn-34cb711ba922f53cca45443b8c3c1078873cf599.zip | |
[NET]: Disable NET_SCH_CLK_CPU for SMP x86 hosts
Opterons with frequency scaling have fully unsynchronized TSCs
running at different frequencies, so using TSCs there is not a good idea.
Also some other x86 boxes have this problem. gettimeofday should be good
enough, so just disable it.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/Kconfig | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/sched/Kconfig b/net/sched/Kconfig index 45d3bc0812c8..81510da31792 100644 --- a/net/sched/Kconfig +++ b/net/sched/Kconfig @@ -72,9 +72,11 @@ config NET_SCH_CLK_GETTIMEOFDAY Choose this if you need a high resolution clock source but can't use the CPU's cycle counter. +# don't allow on SMP x86 because they can have unsynchronized TSCs. +# gettimeofday is a good alternative config NET_SCH_CLK_CPU bool "CPU cycle counter" - depends on X86_TSC || X86_64 || ALPHA || SPARC64 || PPC64 || IA64 + depends on ((X86_TSC || X86_64) && !SMP) || ALPHA || SPARC64 || PPC64 || IA64 help Say Y here if you want to use the CPU's cycle counter as clock source. This is a cheap and high resolution clock source, but on some |