Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756769AbZA2ImX (ORCPT ); Thu, 29 Jan 2009 03:42:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753372AbZA2ImO (ORCPT ); Thu, 29 Jan 2009 03:42:14 -0500 Received: from out5.smtp.messagingengine.com ([66.111.4.29]:47445 "EHLO out5.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753142AbZA2ImN (ORCPT ); Thu, 29 Jan 2009 03:42:13 -0500 Date: Thu, 29 Jan 2009 19:42:10 +1100 From: Bron Gondwana To: Davide Libenzi Cc: Linux Kernel Mailing List , Linus Torvalds , Andrew Morton , Greg KH , Willy Tarreau , Michael Kerrisk , Bron Gondwana Subject: Re: [patch] drop epoll max_user_instances and rely only on max_user_watches Message-ID: <20090129084210.GA2704@brong.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: brong.net User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1268 Lines: 31 On Wed, Jan 28, 2009 at 08:56:07PM -0800, Davide Libenzi wrote: > Linus suggested to put limits where the money is, and max_user_watches > already does that w/out the need of max_user_instances. That has the > advantage to mitigate the potential DoS while allowing pretty generous > default behavior. > Allowing top 4% of low memory (per user) to be allocated in epoll > watches, we have: > > LOMEM MAX_WATCHES (per user) > 512MB ~178000 > 1GB ~356000 > 2GB ~712000 > > A box with 512MB of lomem, will meet some challenge in hitting 180K > watches, socket buffers math teaches us. > No more max_user_instances limits then. Excellent. Glad to see :) Saves me from keeping on working on my "only account epoll within epoll for max_user_instances" patch, which would have just been needless complexity (though cheap - is_file_epoll looks pretty easy to check for both descriptors) - and I hadn't even compiled and tested it yet. Thanks Davide - this will keep our mxes humming along happily. Bron. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/