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  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:	Wed, 17 Nov 2010 11:15:21 -0500
From:	Steven Rostedt <>
To:	Peter Zijlstra <>
Cc:	Ingo Molnar <>, Ted Ts'o <>,
	Thomas Gleixner <>,
	LKML <>,
	Linus Torvalds <>,
	Andrew Morton <>,
	Arjan van de Ven <>,
	Arnaldo Carvalho de Melo <>,
	Frederic Weisbecker <>,
	Masami Hiramatsu <>,
	Tom Zanussi <>,
	Mathieu Desnoyers <>,
	Li Zefan <>,
	Jason Baron <>,
	"David S. Miller" <>,
	Christoph Hellwig <>,
	Pekka Enberg <>,
	Lai Jiangshan <>,
	Eric Dumazet <>
Subject: Re: [ANNOUNCE] New utility: 'trace'

On Wed, 2010-11-17 at 16:43 +0100, Peter Zijlstra wrote:
> On Wed, 2010-11-17 at 10:10 -0500, Steven Rostedt wrote:
> > 
> > Right, the problem with filtering is what do we want to filter, and what
> > about copying?
> > 
> > Currently, we copy the data into the buffer and then filter on that
> > data. We could also easily filter on the parameters of the tracepoint,
> > but sometimes those parameters do not match the final output (as the
> > case with sched_switch). Do we copy the data into a separate "per cpu"
> > temp buffer, and figure out the filter then? And if the filter is fine,
> > then copy into the buffer. This obviously is slow, due to the multiple
> > copies. We could do this only if the filtering is enabled.
> Right, so what is the primary purpose of this filtering stuff? As it
> stands it makes stuff terribly slow, so you add overhead but the win
> (presumably) is less data output, is that a sane trade-off?

I've actually used filtering too. Not for speed up, but because I was
recording a lot of data and the reader could not keep up. By filtering,
I was able to get all the relevant information without needing to make
the kernel buffer a Gig.

-- Steve

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists