From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [Xen-devel] [PATCH net-next 1/3] xen-netback: page pool support Date: Fri, 24 May 2013 13:44:31 +0100 Message-ID: <519F60AF.5020705@citrix.com> References: <1369391553-16835-1-git-send-email-wei.liu2@citrix.com> <1369391553-16835-2-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , , , To: Wei Liu Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:29431 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752248Ab3EXMoe (ORCPT ); Fri, 24 May 2013 08:44:34 -0400 In-Reply-To: <1369391553-16835-2-git-send-email-wei.liu2@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On 24/05/13 11:32, Wei Liu wrote: > This patch implements a page pool for all vifs. It has two functionalities: > a) to limit the amount of pages used by all vifs > b) to track pages belong to vifs This adds a global spin lock. This doesn't seem very scalable. It's also not clear how this is usefully limiting the memory usage by guest network traffic. It limits the number of pages that netback can use during the grant copy from the guest pages but this is only short time compared to the lifetime of the network packet within the rest of the network stack. If you didn't have this page pool stuff then each thread/VIF is limited to at most 256 pages anyway and I think 1 MiB of memory per VIF is perfectly acceptable. David