cgroup support for physical_processor_count #1035
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eregon
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Jan 22, 2024
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| if Dir.exist?("/sys/fs/cgroup/cpu,cpuacct") && (cfs_quota_us = IO.read("/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_quota_us").to_i) > 0 | ||
| (cfs_quota_us / IO.read("/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_period_us").to_i.to_f).ceil |
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Is there some documentation about these cgroups files?
It'd be nice to add a link as a code comment here.
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| if Dir.exist?("/sys/fs/cgroup/cpu,cpuacct") && (cfs_quota_us = IO.read("/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_quota_us").to_i) > 0 | ||
| (cfs_quota_us / IO.read("/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_period_us").to_i.to_f).ceil |
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.to_i.to_f can probably be just .to_f
| elsif ln.start_with?("core") | ||
| cid = phy + ":" + ln[/\d+/] | ||
| cores[cid] = true if not cores[cid] | ||
| if Dir.exist?("/sys/fs/cgroup/cpu,cpuacct") && (cfs_quota_us = IO.read("/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_quota_us").to_i) > 0 |
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Could you use File.read instead of IO.read? It seems clearer (same on the next line).
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It works as expected inside a container limited to 3 cores running in a host machine that has over 10: |
byroot
reviewed
Jan 29, 2024
| cid = phy + ":" + ln[/\d+/] | ||
| cores[cid] = true if not cores[cid] | ||
| # https://kernel.googlesource.com/pub/scm/linux/kernel/git/glommer/memcg/+/cpu_stat/Documentation/cgroups/cpu.txt | ||
| if Dir.exist?("/sys/fs/cgroup/cpu,cpuacct") && (cfs_quota_us = File.read("/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_quota_us").to_i) > 0 |
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IMO we shouldn't change the behavior of physical_processor_count. We should instead have a cpu_quota method that returns a float, and then eventually a usable_processor_count which returns cpu_quota * processor_count.
This way it's up to the caller to decide if they want to floor/round/ceil
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Also I think what you implemented here is cgroups V1? Not sure how much it's used these days, in cgroups V2 the info is in /sys/fs/cgroup/cpu.max.
casperisfine
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Closes: ruby-concurrency#1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
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I took the liberty to push this a bit further in #1038 with cgroups v2 support etc. |
casperisfine
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Closes: ruby-concurrency#1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
casperisfine
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Jan 29, 2024
Closes: ruby-concurrency#1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
casperisfine
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Jan 29, 2024
Closes: ruby-concurrency#1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
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Thank you for the PR, let's continue this on #1038 |
casperisfine
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Feb 1, 2024
Closes: ruby-concurrency#1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
casperisfine
pushed a commit
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that referenced
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Feb 1, 2024
Closes: ruby-concurrency#1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
eregon
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Feb 1, 2024
Closes: #1035 A running gag since the introduction of containerization is software that starts one process per logical or physical core while running inside a container with a restricted CPU quota and totally blowing up memory usage in containerized environments. The proper question to ask is how many CPU cores are usable, not how many the machine has. To do that we have to read the cgroup info from `/sys`. There is two way of doing it depending on the version of cgroups used. Co-Authored-By: usiegl00 <50933431+usiegl00@users.noreply.github.com>
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As rails depends on
physical_processor_countto spin up the right number of puma workers, rails will fall over in a containerized environment where cgroups are used to limit cpu time. This pr is an attempt to accurately reflect the available cpu cores when the ruby process is running inside a cgroup.