From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: Page Allocation Failure with e1000 using jumbo frame Date: Fri, 19 Aug 2005 10:03:08 -0700 Message-ID: <430610CC.50709@us.ibm.com> References: <1124326404.5546.215.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Ming Zhang , E1000 , iet-dev , netdev@vger.kernel.org Return-path: To: Jesse Brandeburg In-Reply-To: Sender: e1000-devel-admin@lists.sourceforge.net Errors-To: e1000-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: List-Id: netdev.vger.kernel.org Jesse Brandeburg wrote: > included netdev... > > > On Wed, 17 Aug 2005, Ming Zhang wrote: > >> >> Hi folks >> >> We ran into this problem when running jumbo frame with iscsi over e1000. >> the MTU1500 is fine while jumbo frame can stably reproduce this error. >> >> when meet this error, as reported in iet list, the box still has >600MB >> ram free. also the slab is not heavily used. >> >> any idea on this? > > > > So, what we do know is that your kernel memory manager is (for whatever > unknown reason) having trouble finding contiguous 2^3 pages (32kB) > chunks of memory. This occurs because we need to give our hardware 16kB > contiguous (currently, we actually have a patch for this in internal > testing) which means that when we do dev_alloc_skb, it allocates 16kB + > 16 bytes reserve, plus 2 bytes NET_IP_ALIGN, which takes us into the > 32kB slab (power of two roundup) > > I guess we need to approach the memory manager guys and ask them why the > current kernels are having so much trouble getting contiguous memory. > Also, recently thanks to David Miller's discussions on socket charge, we > understand that we're getting hit hard by using such a big buffer. > > Netdev any ideas? Interesting you should mention this, I just mentioned it in the context of another thread like 3 seconds ago. I've talked to Martin Bligh in the past about having the VM do something sane about these to improve the situation - I'll go kick, er, ping him again... The current status is "try not to do that" (large contig allocs). If anyone has any good ideas, speak up :) thanks, Nivedita ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf