linux-kernel - Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on

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]

Message-ID: <20160224140239.GT6375@twins.programming.kicks-ass.net>
Date:	Wed, 24 Feb 2016 15:02:39 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Pratyush Anand <panand@...hat.com>
Cc:	Jiri Olsa <jolsa@...hat.com>, mingo@...nel.org,
	alexander.shishkin@...ux.intel.com, eranian@...gle.com,
	linux-kernel@...r.kernel.org, vince@...ter.net, dvyukov@...gle.com,
	andi@...stfloor.org, sasha.levin@...cle.com, oleg@...hat.com
Subject: Re: [RFC][PATCH 4/7] perf: Fix scaling vs enable_on_exec

On Wed, Feb 24, 2016 at 12:53:51PM +0100, Peter Zijlstra wrote:
> On Tue, Feb 23, 2016 at 06:47:41PM +0100, Peter Zijlstra wrote:
> > On Tue, Feb 23, 2016 at 10:05:50PM +0530, Pratyush Anand wrote:
> > > Its better with this patch, still count is 1 more in case of higher probe hits (
> > > like 65535 times).
> > 
> > Ah, ok, I'll go try again.
> 
> OK, so the below seems to cure this for me, but now I'm hurting my head
> to make the same true for perf_install_in_context(), because 'tricky' :/
> 

FWIW, it would be nice to have a similar test for:

	attr = {
		.disabled = true;
	}

	sys_perf_event_open(&attr, .pid = self);

	if (attr.disabled)
		ioctl(ENABLE);

	/* generate N events */

	ioctl(DISABLE);

	read();

	/* print event cnt and scale factors */

and one that has .disabled = false.