Linux's perf subsystem, about which you can read a lot more here https://www.brendangregg.com/perf.html is an invaluable subsystem for tracing the performance of the kernel and user-space code.
It's a bit of the wild-west, it's a fast moving space with lots of moving pieces, and lots of unusual kernel- and user-space interop which makes it tricky to use.
What makes it trickier unfortunately is that Canonical saw fit to remove scripting support from the perf tool in the linux-tools-generic (and linux-tools-$(name -r)) package rendering it practically useless.
Confirm you have this problem with the following:
sudo perf script -s lang Scripting language extensions (used in perf script -s [spec:]script.[spec]): Perl [Perl] pl [Perl] Python [Python] py [Python] Great, seems like perf script has Python and Perl support, right? ... not quite:
The steps here can be also used to enable Perl scripting support, but I'm sticking with Python, since what little documentation there is covers this specifically.
sudo perf script -g py Python scripting not supported. Install libpython and rebuild perf to enable it. For example: # apt-get install python-dev (ubuntu) # yum install python-devel (Fedora) etc. Unfortunately the instructions won't help you and there's no way to rebuild the linux-tools-* packages easily even after adding the {python,perl}-dev{,el} packages as suggested.
Rather one is required to get the kernel sources, and patch them and then re-build the entire kernel package tree and then and only then can a version of linux-tools-* with scripting support be installed:
The instructions ultimately are the normal instructions for building a new kernel; but I'll drop a block of shell commands below to save having to read a bunch of convolouted docs with multiple options:
- Follow to about half way: https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel
- Modify a file to remove
NO_LIBPYTHON=1(note it must be REMOVED, not set to0) - Compile the kernel from that source tree (resume the build your own kernel guide)
- Install the
linux-toolspackage withdpkg -i ..from the newly built packages.
So:
# 1. enable deb sources in /etc/sources.list sed -i '/deb-src/s/^# //' /etc/apt/sources.list && apt update # 2. install kernel sources for current kernel (installs to $PWD) e.g ./linux-5.4.0 apt-get source linux-image-unsigned-$(uname -r) # 3. install python-dev package & general kernel build deps apt install python-dev libncurses-dev gawk flex bison openssl libssl-dev dkms libelf-dev libudev-dev libpci-dev libiberty-dev autoconf default-jdk # 4. change into the directory cd ./linux-generic-5.4.0 # 5. apply this patch: patch -p1 << EOPATCH --- ./debian/rules.d/2-binary-arch.mkbak 2022-01-26 09:40:31.791079823 +0100 +++ ./debian/rules.d/2-binary-arch.mk 2022-01-26 09:40:46.671072005 +0100 @@ -702,7 +702,7 @@ cd $(builddirpa) && $(kmake) syncconfig cd $(builddirpa) && $(kmake) prepare cd $(builddirpa)/tools/perf && \ - $(kmake) prefix=/usr HAVE_NO_LIBBFD=1 HAVE_CPLUS_DEMANGLE_SUPPORT=1 CROSS_COMPILE=$(CROSS_COMPILE) NO_LIBPYTHON=1 NO_LIBPERL=1 + $(kmake) prefix=/usr HAVE_NO_LIBBFD=1 HAVE_CPLUS_DEMANGLE_SUPPORT=1 CROSS_COMPILE=$(CROSS_COMPILE) NO_LIBPERL=1 endif ifeq ($(do_tools_bpftool),true) $(kmake) CROSS_COMPILE=$(CROSS_COMPILE) -C $(builddirpa)/tools/bpf/bpftool EOPATCH # 6. Build the targets # if this fails and you need to install new deps, then # reset things with `fakeroot debian/rules clean` fakeroot debian/rules binary-arch # 7. Wait (about 15-20 minutes on a decent laptop, probably, YMMV with virtualization) # 8. Install the new package with dpkg -i # note: filename here varies a lot by version and arch sudo dpkg -i linux-tools-*.deb After all this then the command sudo perf script -g py should generate a pyton script with hooks for any perf recorders you might have enabled already.
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