Date: Mon, 27 Oct 2014 13:37:24 -0700 From: Brendan Gregg <brendan.d.gregg@gmail.com> To: freebsd-performance@freebsd.org Subject: pmcstat -z32 -G truncates callgraph to 8 Message-ID: <CAE40pdf5AzR4tuGZUQugoK6jfbvd_dLLBtdfv2FPQYY3Lb5PrA@mail.gmail.com>
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G'Day, I'm using pmcstat to capture call graphs, however, these always seem truncated to 8 stack frames. Anyone else hit this? Anyone know a fix or workaround? Example: pmcstat -S CPU_CLK_UNHALTED.THREAD_P -z 32 -O out.pmclog pmstat -R out.pmclog -z 32 -G out.pmc The problem is that out.pmc never goes deeper than 8 frames, despite -z 32, and despite PMC_CALLCHAIN_DEPTH_MAX = 32. I need deeper stacks to generate flame graphs (https://github.com/brendangregg/FlameGraph), and was trying Ed Maste's stackcollapse-pmc.pl to do it. Using pmcstat -F, and bringing up the output in Kcachegrind, shows that some stacks are indeed deeper than 8 as expected (although it seems to only work for kernel stacks, and not user-level). I don't know if Kcachegrind is doing its own workaround, of if the -F output is deeper than -G (still studying the output formats)... thanks, Brendan
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