From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [RFC][PATCH 2/9] deadlock prevention core Date: Thu, 17 Aug 2006 23:05:56 -0700 Message-ID: <20060817230556.7d16498e.akpm@osdl.org> References: <20060808211731.GR14627@postel.suug.ch> <44DBED4C.6040604@redhat.com> <44DFA225.1020508@google.com> <20060813.165540.56347790.davem@davemloft.net> <44DFD262.5060106@google.com> <20060813185309.928472f9.akpm@osdl.org> <1155530453.5696.98.camel@twins> <20060813215853.0ed0e973.akpm@osdl.org> <44E3E964.8010602@google.com> <20060816225726.3622cab1.akpm@osdl.org> <44E5015D.80606@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Peter Zijlstra , David Miller , riel@redhat.com, tgraf@suug.ch, linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Mike Christie Return-path: Received: from smtp.osdl.org ([65.172.181.4]:61314 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751131AbWHRGMs (ORCPT ); Fri, 18 Aug 2006 02:12:48 -0400 To: Daniel Phillips In-Reply-To: <44E5015D.80606@google.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 17 Aug 2006 16:53:01 -0700 Daniel Phillips wrote: > Andrew Morton wrote: > > Daniel Phillips wrote: > >>What happened to the case where we just fill memory full of dirty file > >>pages backed by a remote disk? > > > > Processes which are dirtying those pages throttle at > > /proc/sys/vm/dirty_ratio% of memory dirty. So it is not possible to "fill" > > memory with dirty pages. If the amount of physical memory which is dirty > > exceeds 40%: bug. > > Hi Andrew, > > So we make 400 MB of a 1 GB system by default - it's runtime configurable. > unavailable for write caching just to > get around the network receive starvation issue? No, it's mainly to avoid latency: to prevent tasks which want to allocate pages from getting stuck behind writeback. > What happens if some in kernel user grabs 68% of kernel memory to do some > very important thing, does this starvation avoidance scheme still work? Well something has to give way. The process might get swapped out a bit, or it might stall in the page allocator because of all the dirty memory.