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45 lines
1.6 KiB
Markdown
45 lines
1.6 KiB
Markdown
# Using the perf utility with LinuxKit
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The `perf` utility is a standard Linux tool to access performance
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counters, trace events and access various other kernel internals for
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performance analysis.
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The `perf` utility needs to matched be with the kernel. For recent
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kernel build, LinuxKit provides a `linuxkit/kernel-perf` package with
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a matching tag for each kernel under `linuxkit/kernel`.
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There are a number of ways to use `linuxkit/kernel-perf` package:
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1. Add it to the `init` section. This adds `/usr/bin/perf` to the
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systems' root filesystem. From there it can be
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- bind mounted into your container
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- accessed via `/proc/1/root/usr/bin/perf` from with in the `getty`
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or `ssh` container.
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2. Add it to you package. If you have a custom package already, you
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can add `linuxkit/kernel-perf` as another stage in your package and
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then copy `/usr/bin/perf` into the final stage.
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The first method is preferable since you need to match with the kernel
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package tag and that is typically defined in the YAML file. I
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typically don't add the bind mount since this requires further
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modification and simply create a symlink in the `ssh` or `getty` container:
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```
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ln -s /proc/1/root/usr/bin/perf /usr/bin/perf
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```
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If you want to use `perf` you may also want to remove the `sysctl`
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container, or alternatively, disable the kernel pointer restriction it
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enables by default:
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```
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echo 0 > /proc/sys/kernel/kptr_restrict
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```
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Now, `perf` is ready to use. The LinuxKit `perf` package only contains
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the `perf` binary, but excludes the detailed help messages or
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additional scripts. If there is demand, we can add them to the
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LinuxKit package.
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