[Bug] [KNL] ~5x slowdown of application when attaching by perf on KNL

Bug #1730782 reported by quanxian on 2017-11-08
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
intel
Undecided
Unassigned
linux (Ubuntu)
Medium
Canonical Kernel Team
Bionic
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://www.spinics.net/lists/kernel/msg2552460.html
https://www.spinics.net/lists/kernel/msg2552461.html
https://www.spinics.net/lists/kernel/msg2552462.html
https://www.spinics.net/lists/kernel/msg2552463.html

Target kernel: TBD
Target Release: 19.04

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

A v9 was posted on August 31st, but there is still no progress upstream. Meanwhile, Peter Zijlstra merged 0d3d73aac2ff05c78387aa9dcc2c8aa3804405e7 ("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.

quanxian (quanxian-wang) on 2018-05-01
description: updated
tags: added: intel-kernel-18.10
Changed in intel:
status: New → Won't Fix
quanxian (quanxian-wang) wrote :

the patch of this bug is under review in upstream. Once update is official, we will provide patch commit id in this bug. This bug is for tracking. Thanks for your support.

quanxian (quanxian-wang) on 2018-10-24
Changed in intel:
status: Won't Fix → New
tags: added: intel-kernel-19.04
removed: intel-kernel-18.10
description: updated
To post a comment you must log in.
This report contains Public information  Edit
Everyone can see this information.

Other bug subscribers