Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754368AbbESP00 (ORCPT ); Tue, 19 May 2015 11:26:26 -0400 Received: from smtp.citrix.com ([66.165.176.89]:59664 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753140AbbESP0X (ORCPT ); Tue, 19 May 2015 11:26:23 -0400 X-IronPort-AV: E=Sophos;i="5.13,458,1427760000"; d="scan'208";a="264065088" Message-ID: <555B5601.5020906@citrix.com> Date: Tue, 19 May 2015 16:25:53 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0 MIME-Version: 1.0 To: Julien Grall , CC: , , , , David Vrabel , Boris Ostrovsky , Subject: Re: [Xen-devel] [RFC 16/23] xen/events: fifo: Make it running on 64KB granularity References: <1431622863-28575-1-git-send-email-julien.grall@citrix.com> <1431622863-28575-17-git-send-email-julien.grall@citrix.com> In-Reply-To: <1431622863-28575-17-git-send-email-julien.grall@citrix.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1161 Lines: 29 On 14/05/15 18:00, 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 > > 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 think you want an xen_alloc_page_for_xen() or similar to allocate a 4 KiB size/aligned block. But as-is: Reviewed-by: David Vrabel 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/