Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > linux.kernel > #1687594

Re: perf: bisected sampling bug in Linux 4.11-rc1

From Vince Weaver <vincent.weaver@maine.edu>
Newsgroups linux.kernel
Subject Re: perf: bisected sampling bug in Linux 4.11-rc1
Date 2017-07-14 20:30 +0200
Message-ID <u3dvH-7f8-1@gated-at.bofh.it> (permalink)
References <u3dcm-75z-29@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw


On Fri, 14 Jul 2017, Vince Weaver wrote:

> On a good kernel you get the following:
> 	Event perf::instructions with period 1000000
> 	Event perf::instructions with period 2000000
> 		fd 3 overflows: 946 (perf::instructions/1000000)
> 		fd 4 overflows: 473 (perf::instructions/2000000)
> 	Ending counts:
> 		Count 0: 946379875
> 		Count 1: 946365218
> 
> With the broken kernels you get:
> 	Event perf::instructions with period 1000000
> 	Event perf::instructions with period 2000000
> 		fd 3 overflows: 938 (perf::instructions/1000000)
> 		fd 4 overflows: 318 (perf::instructions/2000000)
> 	Ending counts:
> 		Count 0: 946373080
> 		Count 1: 653373058

additional relevant detail:
	in the failing case, the group leader of the event set has 
		.pinned=1
	If I change that to .pinned=0 then the test passes.

Vince

Back to linux.kernel | Previous | NextPrevious in thread | Next in thread | Find similar | Unroll thread


Thread

perf: bisected sampling bug in Linux 4.11-rc1 Vince Weaver <vincent.weaver@maine.edu> - 2017-07-14 20:10 +0200
  Re: perf: bisected sampling bug in Linux 4.11-rc1 Vince Weaver <vincent.weaver@maine.edu> - 2017-07-14 20:30 +0200
  Re: perf: bisected sampling bug in Linux 4.11-rc1 Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-07-14 22:10 +0200
    Re: perf: bisected sampling bug in Linux 4.11-rc1 Vince Weaver <vincent.weaver@maine.edu> - 2017-07-14 22:20 +0200
  Re: perf: bisected sampling bug in Linux 4.11-rc1 Ingo Molnar <mingo@kernel.org> - 2017-07-15 13:10 +0200
    Re: perf: bisected sampling bug in Linux 4.11-rc1 Vince Weaver <vincent.weaver@maine.edu> - 2017-07-15 16:40 +0200
      Re: perf: bisected sampling bug in Linux 4.11-rc1 Vince Weaver <vincent.weaver@maine.edu> - 2017-07-16 05:10 +0200

csiph-web