Messages in this thread Patch in this message | | | Date | Fri, 07 Nov 2008 00:23:37 -0500 | From | Mathieu Desnoyers <> | Subject | [RFC patch 01/18] get_cycles() : kconfig HAVE_GET_CYCLES |
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Create a new "HAVE_GET_CYCLES" architecture option to specify which architectures provide 64-bits TSC counters readable with get_cycles(). It's principally useful to only enable high-precision tracing code only on such architectures and don't even bother building it on architectures which lack such support.
It also requires architectures to provide get_cycles_barrier() and get_cycles_rate().
I mainly use it for the "priority-sifting rwlock" latency tracing code, which traces worse-case latency induced by the locking. It also provides the basic changes needed for the LTTng timestamping infrastructure.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: David Miller <davem@davemloft.net> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Andrew Morton <akpm@linux-foundation.org> CC: Ingo Molnar <mingo@redhat.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Thomas Gleixner <tglx@linutronix.de> CC: Steven Rostedt <rostedt@goodmis.org> CC: linux-arch@vger.kernel.org --- init/Kconfig | 10 ++++++++++ 1 file changed, 10 insertions(+)
Index: linux.trees.git/init/Kconfig =================================================================== --- linux.trees.git.orig/init/Kconfig 2008-11-07 00:06:07.000000000 -0500 +++ linux.trees.git/init/Kconfig 2008-11-07 00:07:23.000000000 -0500 @@ -330,6 +330,16 @@ config CPUSETS config HAVE_UNSTABLE_SCHED_CLOCK bool +# +# Architectures with a 64-bits get_cycles() should select this. +# They should also define +# get_cycles_barrier() : instruction synchronization barrier if required +# get_cycles_rate() : cycle counter rate, in HZ. If 0, TSC are not synchronized +# across CPUs or their frequency may vary due to frequency scaling. +# +config HAVE_GET_CYCLES + def_bool n + config GROUP_SCHED bool "Group CPU scheduler" depends on EXPERIMENTAL -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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