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authorAndi Kleen <ak@suse.de>2005-10-13 17:41:44 -0400
committerDavid S. Miller <davem@davemloft.net>2005-10-13 17:41:44 -0400
commit34cb711ba922f53cca45443b8c3c1078873cf599 (patch)
tree2b120d59460047caff9546d68f445626947d47fc /net
parentc8923c6b852d3a97c1faad0566e38fca330375a7 (diff)
[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')
-rw-r--r--net/sched/Kconfig4
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
72 Choose this if you need a high resolution clock source but can't use 72 Choose this if you need a high resolution clock source but can't use
73 the CPU's cycle counter. 73 the CPU's cycle counter.
74 74
75# don't allow on SMP x86 because they can have unsynchronized TSCs.
76# gettimeofday is a good alternative
75config NET_SCH_CLK_CPU 77config NET_SCH_CLK_CPU
76 bool "CPU cycle counter" 78 bool "CPU cycle counter"
77 depends on X86_TSC || X86_64 || ALPHA || SPARC64 || PPC64 || IA64 79 depends on ((X86_TSC || X86_64) && !SMP) || ALPHA || SPARC64 || PPC64 || IA64
78 help 80 help
79 Say Y here if you want to use the CPU's cycle counter as clock source. 81 Say Y here if you want to use the CPU's cycle counter as clock source.
80 This is a cheap and high resolution clock source, but on some 82 This is a cheap and high resolution clock source, but on some