Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754867AbbHFPop (ORCPT ); Thu, 6 Aug 2015 11:44:45 -0400 Received: from smtp.citrix.com ([66.165.176.89]:5470 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754461AbbHFPon (ORCPT ); Thu, 6 Aug 2015 11:44:43 -0400 X-IronPort-AV: E=Sophos;i="5.15,623,1432598400"; d="scan'208";a="288783599" Message-ID: <55C38093.8080609@citrix.com> Date: Thu, 6 Aug 2015 16:43:15 +0100 From: Julien Grall User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.8.0 MIME-Version: 1.0 To: David Vrabel , CC: , , , Boris Ostrovsky , Subject: Re: [Xen-devel] [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> <55B21527.4010601@citrix.com> In-Reply-To: <55B21527.4010601@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: 1359 Lines: 38 Hi David, On 24/07/15 11:36, David Vrabel wrote: > 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 Thank you! >> >> 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. I will keep it in mind when I will send a patch to reduce memory waster. Regards, -- Julien Grall -- 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/