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From: Max Kellermann <max@duempel.org>
To: Natanael Copa <mlists@tanael.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: forkbombing Linux distributions
Date: Wed, 23 Mar 2005 15:52:04 +0100	[thread overview]
Message-ID: <20050323145204.GA23661@roonstrasse.net> (raw)
In-Reply-To: <1111589098.27969.100.camel@nc>

On 2005/03/23 15:44, Natanael Copa <mlists@tanael.org> wrote:
> Yes, but if 
> RLIMIT_NPROC is per user and RLIMIT_CPU is per proc
> 
> the theoretical CPU limit per user is RLIMIT_NPROC * RLIMIT_CPU. So if
> you half the RLIMIT_NPROC you will half the theoretical maximum CPU
> limit per user.
> 
> Same with memory.

It's even worse with RLIMIT_CPU. Imagine a process forks
RLIMIT_NPROC-1 child processes. These consume all their CPU time, get
killed with SIGXCPU, and the parent process spawns new child processes
again with fresh RLIMIT_CPU counters (the parent process idled
meanwhile, consuming none of its assigned CPU cycles). Again and
again.

You see, RLIMIT_CPU is worthless in its current implementation.

Max


  reply	other threads:[~2005-03-23 14:57 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-21  3:06 forkbombing Linux distributions William Beebe
2005-03-21  3:22 ` Dave Jones
2005-03-21  3:26   ` William Beebe
2005-03-21  3:27 ` Peter Chubb
2005-03-21  5:14   ` Grant Coady
2005-03-21  7:41     ` Jan Engelhardt
2005-03-22 11:26 ` Hikaru1
2005-03-22 11:49   ` Jan Engelhardt
     [not found]     ` <20050322124812.GB18256@roll>
2005-03-22 12:50       ` Hikaru1
2005-03-23 10:56         ` aq
2005-03-23 12:37           ` Natanael Copa
2005-03-23 13:04             ` aq
2005-03-23 13:38               ` Jan Engelhardt
2005-03-23 13:54               ` Natanael Copa
2005-03-23 14:20                 ` Måns Rullgård
2005-03-23 14:43                 ` Jan Engelhardt
2005-03-23 15:04                   ` Natanael Copa
2005-03-24  7:07                     ` Jan Engelhardt
2005-03-24 10:05                       ` Natanael Copa
2005-03-23 19:38                   ` Kyle Moffett
2005-03-23 20:26                     ` Natanael Copa
2005-03-23 17:05                 ` aq
2005-03-23 18:05                   ` Paul Jackson
2005-03-23 18:44                     ` aq
2005-03-23 20:15                       ` Natanael Copa
2005-03-23 20:48                   ` Natanael Copa
2005-03-23 13:45             ` Erik Mouw
2005-03-23 14:03               ` Natanael Copa
2005-03-23 13:53     ` Max Kellermann
2005-03-23 14:23       ` Natanael Copa
2005-03-23 14:27         ` Max Kellermann
2005-03-23 14:44           ` Natanael Copa
2005-03-23 14:52             ` Max Kellermann [this message]
2005-03-23 15:18               ` Natanael Copa
2005-03-26 10:37 ` Tux
2005-03-28  8:03   ` Natanael Copa
  -- strict thread matches above, loose matches on Subject: below --
2005-03-22 17:09 Natanael Copa
2005-03-28 17:28 Matthieu Castet
2005-03-28 17:56 ` folkert
2005-03-28 19:33   ` Jan Engelhardt
2005-03-28 19:39     ` folkert
2005-03-28 20:35       ` Renate Meijer
2005-03-29 12:31 ` Natanael Copa
2005-03-30 23:46 ` Felipe Alfaro Solana
2005-03-31  6:55   ` Natanael Copa
2005-03-31  7:09     ` Jacek Łuczak
2005-03-30 17:40 Jacek Łuczak
2005-03-31 10:00 ` Natanael Copa
2005-03-31 17:11   ` Lee Revell
2005-04-05  9:47     ` Natanael Copa
2005-04-05 10:18       ` Jacek Luczak

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