netdev - Re: iperf: performance regression (was b44 driver problem?)

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: <200706042148.02450.maxi@daemonizer.de>
Date:	Mon, 4 Jun 2007 21:47:59 +0200
From:	Maximilian Engelhardt <maxi@...monizer.de>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Stephen Hemminger <shemminger@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ulrich Drepper <drepper@...il.com>,
	Michael Buesch <mb@...sch.de>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Jeff Garzik <jgarzik@...ox.com>,
	Gary Zambrano <zambrano@...adcom.com>, netdev@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: iperf: performance regression (was b44 driver problem?)

On Monday 04 June 2007, Ingo Molnar wrote:
> * Stephen Hemminger <shemminger@...ux-foundation.org> wrote:
> > Yes, the following patch makes iperf work better than ever. But are
> > other broken applications going to have same problem. Sounds like the
> > old "who runs first" fork() problems.
>
> this is the first such app and really, and even for this app: i've been
> frequently running iperf on -rt kernels for _years_ and never noticed
> how buggy its 'locking' code was, and that it would under some
> circumstances use up the whole CPU on high-res timers.

I must admit I don't know much about that topic, but there is one thing I 
don't understand. Why is iperf (even if it's buggy) able to use up the whole 
cpu? I didn't run it as root but as my normal user so it should have limited 
rights. Shouldn't the linux scheduler distribute cpu time among all running 
processes?

Maxi

Download attachment "signature.asc " of type "application/pgp-signature" (190 bytes)