Date: Thu, 23 Feb 2006 10:19:51 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Robert Watson <rwatson@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: The sixty second pmc howto Message-ID: <17405.53911.686306.362353@grasshopper.cs.duke.edu> In-Reply-To: <20060223143856.O9642@fledge.watson.org> References: <20060223143856.O9642@fledge.watson.org>
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Robert Watson writes: > (2) Run "pmcstat -S instructions -O /tmp/sample.out" to start sampling of > instruction retirement events, saving the results to /tmp/sample.out. Dumb question, but what does "instructions" really mean? The number of instructions, the time spent executing them, ? <.....> > Since there is no call graph information in the sample, the first few pages of > gprof output will be of limited utility, but the summary table by function is > the bit I found most useful: You can use gprof -l to suppress the printing of the call-graph profile My only problem with hwpmc is that it will not work for kernel modules. I wonder if somebody with enough toolchain fu could take kldstat output and produce a pre-linked elf executable image containing kernel+modules which could be used for hwpmc, and also for crash dump analysis. Or is there another, better, way to get a complete symbol table of the kernel & all kernel modules? > So if you're doing kernel performance work, and not already using pmc, you > probably should be. Very much agreed. Drew
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