Write perfmap and jitdump files to /tmp by default [7.0 port] #89053
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tommcdon
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jeffschwMSFT
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approved. we will take for consideration in 7.0.x. please get codereview
brianrob
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Description
Perfmaps and Jitdumps is a Linux kernel feature that allows .NET to symbolicate dynamically generated code with perf_events. The perfmap/jitdump files are processed by the the Linux
perftool to generate human readable callstacks for CPU traces, for example. The Linux implementation looks for the perfmap/jitdump files in/tmp(please see https://elixir.bootlin.com/linux/v6.4.3/source/tools/perf/util/symbol.c#L1838). The .NET implementation defaults to writing to/tmpbut this can be overridden with the$TMPDIRenvironment variable. This leads to incorrect behavior in environments where$TMPDIRis in use. This code change alters the behavior and will use/tmpregardless of$TMPDIRsettings. There is a minor fix included with this change that correctly sets perfmap location ifDOTNET_PerfMapJitDumpPathis set.This is a port of #88776 from .NET 8
Customer Impact
Internal partner teams have requested this change in .NET servicing
Regression?
Not a regression
Risk
Low, perfmaps+jitdumps is opt-in feature and we are only changing the default location where they are being written to