libct/cg: add CFS bandwidth burst for CPU #3205
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libcontainer/cgroups/fs/cpu.go
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| @@ -89,6 +89,25 @@ func (s *CpuGroup) Set(path string, r *configs.Resources) error { | |||
| period = "" | |||
| } | |||
| } | |||
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| var burst string | |||
| if r.CpuBurst != 0 { | |||
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the spec (in opencontainers/runtime-spec#1120) says
A value of
0for indicates that the cgroup can not accumulate any unused bandwidth. It makes the traditional bandwidth control behavior unchanged.
but since we ignore 0 here, this means we can't disable burst during runc update.
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Good catch, thanks! Yes, I just realized after submitting this so I updated the spec accordingly to elaborate.
update.go
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| // sense, but historically runc allowed it and this needs to be | ||
| // supported to not break compatibility. |
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This is historically true for period and quota, but not for burst. I think we should require period to be set when setting burst.
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Thanks, make sense to me. JFYI, underneath in kernel implementation, it looks like quota, period and burst are all set together. As for systemd, it's not yet supported for burst.
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Is there any new update about this PR？ I think maybe I can help about this PR |
@Zheaoli Thanks for raising this! I'd love to move the PR forward but actually we need to have the spec (opencontainers/runtime-spec#1120) discussed and merged first. Besides I also received the same feature request from @litianxi who aims to apply this in their production and we discussed further offline. @kolyshkin would you please kindly help review the runtime-spec? Thanks a lot. |
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After opencontainers/runtime-spec#1120 has been completed, I think this PR is ready to go |
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Rebased on top of the latest main. |
Burstable CFS controller is introduced in Linux 5.14. This helps with parallel workloads that might be bursty. They can get throttled even when their average utilization is under quota. And they may be latency sensitive at the same time so that throttling them is undesired. This feature borrows time now against the future underrun, at the cost of increased interference against the other system users, by introducing cfs_burst_us into CFS bandwidth control to enact the cap on unused bandwidth accumulation, which will then used additionally for burst. The patch adds the support/control for CFS bandwidth burst. runtime-spec: opencontainers/runtime-spec#1120 Signed-off-by: Kailun Qin <kailun.qin@intel.com>
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Can't be compiled |
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Also please consider adding an integration test |
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@kailun-qin Could you update the PR? |
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@AkihiroSuda, I will take handle of this PR... |
[Carry #3205] libct/cg: add CFS bandwidth burst for CPU
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@AkihiroSuda After #3749 has been merged, I think this PR and #3145 should be closed. |
Burstable CFS controller is introduced in Linux 5.14. This helps with
parallel workloads that might be bursty. They can get throttled even
when their average utilization is under quota. And they may be latency
sensitive at the same time so that throttling them is undesired.
This feature borrows time now against the future underrun, at the cost
of increased interference against the other system users, by introducing
cfs_burst_us into CFS bandwidth control to enact the cap on unused
bandwidth accumulation, which will then used additionally for burst.
The patch adds the support/control for CFS bandwidth burst.
runtime-spec: opencontainers/runtime-spec#1120
Signed-off-by: Kailun Qin kailun.qin@intel.com