linux-kernel - Re: perf: regression with PERF_EVENT_IOC

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 29 May 2011 12:54:00 -0400 (EDT)
From:	Vince Weaver <vweaver1@...s.utk.edu>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, paulus@...ba.org,
	acme@...hat.com
Subject: Re: perf: regression with PERF_EVENT_IOC_REFRESH

On Sat, 28 May 2011, Peter Zijlstra wrote:

> On Fri, 2011-05-27 at 23:38 -0400, Vince Weaver wrote:
> > on that note (and while trying to document exactly what the ioctls do) it 
> > seems that a PERF_EVENT_IOC_REFRESH with an argument of anything higher 
> > than one does not work on kernels 2.6.36 and newer.  The behavior acts
> > as if 1 was passed, even if you pass in, say, 3.
> 
> Urgh, no that should definitely work. Thanks for the test-case, I'll
> work on that (probably not until Monday though, but who knows).
> 

after a painfully long bisection, it turns out that this problem was in
theory introduced by the following commit:

  d57e34fdd60be7ffd0b1d86bfa1a553df86b7172

  perf: Simplify the ring-buffer logic: make perf_buffer_alloc() do everything needed

I'll see if I can come up with a patch, but it's a bit non-obvious why
this commit is affecting the REFRESH value at all.

Vince
vweaver1@...s.utk.edu
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/