[Bug] [KNL] ~5x slowdown of application when attaching by perf on KNL
Bug #1730782 reported by
quanxian
This bug affects 1 person
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
intel |
Fix Released
|
Undecided
|
Unassigned | ||
linux (Ubuntu) |
Triaged
|
Medium
|
Canonical Kernel Team | ||
Bionic |
Triaged
|
Medium
|
Canonical Kernel Team |
Bug Description
Description:
Workload slows down for default sampling cycles in KNL. There are some processing in perf that's single threaded and bottlenecked when number of cores really go up.
A second issue is that things slow down when we issue
perf record – workload
vs
perf record -a – workload
Patch is submitted for review
https:/
https:/
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Target kernel: 4.17
Target Release: 18.10
tags: | added: kernel |
information type: | Proprietary → Public |
Changed in linux (Ubuntu Bionic): | |
status: | New → Triaged |
importance: | Undecided → Medium |
assignee: | nobody → Canonical Kernel Team (canonical-kernel-team) |
tags: | added: bionic kernel-da-key |
description: | updated |
tags: | added: intel-kernel-18.10 |
Changed in intel: | |
status: | New → Won't Fix |
Changed in intel: | |
status: | Won't Fix → New |
tags: |
added: intel-kernel-19.04 removed: intel-kernel-18.10 |
description: | updated |
description: | updated |
description: | updated |
description: | updated |
tags: | added: cscc |
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A v9 was posted on August 31st, but there is still no progress upstream. Meanwhile, Peter Zijlstra merged 0d3d73aac2ff05c 78387aa9dcc2c8a a3804405e7 ("perf/core: Rewrite event timekeeping"), which looks like would have helped with this problem.
Can you confirm if the latest bionic kernel, which has this commit, scales better? If not, what is the plan of pushing this forward upstream?
Cascardo.