提交 34cb711b 编写于 作者: A Andi Kleen 提交者: David S. Miller

[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: NAndi Kleen <ak@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
上级 c8923c6b
...@@ -72,9 +72,11 @@ config NET_SCH_CLK_GETTIMEOFDAY ...@@ -72,9 +72,11 @@ config NET_SCH_CLK_GETTIMEOFDAY
Choose this if you need a high resolution clock source but can't use Choose this if you need a high resolution clock source but can't use
the CPU's cycle counter. 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 config NET_SCH_CLK_CPU
bool "CPU cycle counter" 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 help
Say Y here if you want to use the CPU's cycle counter as clock source. 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 This is a cheap and high resolution clock source, but on some
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