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 for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20090908123610.GA3515@elte.hu>
Date:	Tue, 8 Sep 2009 14:36:10 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	David Miller <davem@...emloft.net>,
	Fr??d??ric Weisbecker <fweisbec@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org, a.p.zijlstra@...llo.nl,
	jens.axboe@...cle.com
Subject: Re: [PATCH 0/2]: Get perf counters working on D-cache aliasing
	cpus.


* David Miller <davem@...emloft.net> wrote:

> With Jen's Axboe's basic sparc counter patch in my tree I started 
> playing with it on sparc64.  Turns out it won't work on anything 
> pre-Niagara.
> 
> The issue is D-cache aliasing between the kernel side mapping and 
> the user side mapping of the perf event ring buffer.
> 
> The following two patches attempt to address this issue and are 
> working properly on my test machine.

Oh, great!

The only (small) worry would be that this uses vmalloc space on 
32-bit platforms which is generally a scarce resource.

IMHO it's not a big issue as the typical workflow would be to have 
just a handful of perf ring-buffers around and most of the 
performance work happens in the 64-bit space anyway.

One practical complication is lots of tracepoints and perf trace: 
but we can solve that via output buffer multiplexing: 
PERF_COUNTER_IOC_SET_OUTPUT - which is implemented in 
tip:perfcounters/core but not yet propagated to the tools. That 
would be desirable to do anyway, to enable time-coherent trace 
entries, etc.

	Ingo
--
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ