Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754112AbbGXKgn (ORCPT ); Fri, 24 Jul 2015 06:36:43 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:58646 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750963AbbGXKgj (ORCPT ); Fri, 24 Jul 2015 06:36:39 -0400 X-IronPort-AV: E=Sophos;i="5.15,538,1432598400"; d="scan'208";a="287214904" Message-ID: <55B21527.4010601@citrix.com> Date: Fri, 24 Jul 2015 11:36:23 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.7.0 MIME-Version: 1.0 To: Julien Grall , CC: , , , , "Konrad Rzeszutek Wilk" , Boris Ostrovsky Subject: Re: [PATCH v2 13/20] xen/events: fifo: Make it running on 64KB granularity References: <1436474552-31789-1-git-send-email-julien.grall@citrix.com> <1436474552-31789-14-git-send-email-julien.grall@citrix.com> In-Reply-To: <1436474552-31789-14-git-send-email-julien.grall@citrix.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1178 Lines: 27 On 09/07/15 21:42, Julien Grall wrote: > Only use the first 4KB of the page to store the events channel info. It > means that we will wast 60KB every time we allocate page for: > * control block: a page is allocating per CPU > * event array: a page is allocating everytime we need to expand it Reviewed-by: David Vrabel > > I think we can reduce the memory waste for the 2 areas by: > > * control block: sharing between multiple vCPUs. Although it will > require some bookkeeping in order to not free the page when the CPU > goes offline and the other CPUs sharing the page still there > > * event array: always extend the array event by 64K (i.e 16 4K > chunk). That would require more care when we fail to expand the > event channel. I would extend it by 4 KiB each time but only allocate a new page every 16 times. This minimizes the resources used in Xen. David -- 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/