Messages in this thread | | | Date | Thu, 21 Sep 2023 09:52:36 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH v7 1/3] x86/fpu: Measure the Latency of XSAVE and XRSTOR |
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> It seems unnecessarily complex: why does it have to measure latency > directly? Tracepoints *by default* come with event timestamps. A latency > measurement tool should be able to subtract two timestamps to extract the > latency between two tracepoints... > > In fact, function tracing is enabled on all major Linux distros: > > kepler:~/tip> grep FUNCTION_TRACER /boot/config-6.2.0-33-generic > CONFIG_HAVE_FUNCTION_TRACER=y > CONFIG_FUNCTION_TRACER=y > > Why not just enable function tracing for the affected FPU context switching > functions?
Or use PT address filters to get it even accurately, as described in [1]. In any case I agree the trace points are not needed.
-Andi
[1] https://lore.kernel.org/lkml/ZPOIVmC6aY9GBtdJ@tassilo/
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