Messages in this thread | | | Date | Mon, 18 Sep 2006 10:53:35 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 0/11] LTTng-core (basic tracing infrastructure) 0.5.108 |
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* Jes Sorensen (jes@sgi.com) wrote: > Mathieu Desnoyers wrote: > > And about those extra cycles.. according to : > > Documentation/kprobes.txt > > "6. Probe Overhead > > > > On a typical CPU in use in 2005, a kprobe hit takes 0.5 to 1.0 > > microseconds to process. Specifically, a benchmark that hits the same > > probepoint repeatedly, firing a simple handler each time, reports 1-2 > > million hits per second, depending on the architecture. A jprobe or > > return-probe hit typically takes 50-75% longer than a kprobe hit. > > When you have a return probe set on a function, adding a kprobe at > > the entry to that function adds essentially no overhead. > [snip] > > So, 1 microsecond seems more like 1500-2000 cycles to me, not 50. > > So call it 2000 cycles, now go measure it in *real* life benchmarks > and not some artificial I call this one syscall that hits the probe > every time in a tight loop, kinda thing. > > Show us some *real* numbers please. >
You are late (I don't blame you about it, considering the size of this thread). It has been posted in the following email :
http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-09/msg04492.html
Mathieu
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