Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758008AbbGQNHt (ORCPT ); Fri, 17 Jul 2015 09:07:49 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:4734 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754335AbbGQNHs (ORCPT ); Fri, 17 Jul 2015 09:07:48 -0400 X-IronPort-AV: E=Sophos;i="5.15,496,1432598400"; d="scan'208";a="285094545" Date: Fri, 17 Jul 2015 14:06:41 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Julien Grall CC: Stefano Stabellini , , , David Vrabel , , Boris Ostrovsky , Subject: Re: [Xen-devel] [PATCH v2 13/20] xen/events: fifo: Make it running on 64KB granularity In-Reply-To: <55A7D955.5090203@citrix.com> Message-ID: References: <1436474552-31789-1-git-send-email-julien.grall@citrix.com> <1436474552-31789-14-git-send-email-julien.grall@citrix.com> <55A7D955.5090203@citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2572 Lines: 71 On Thu, 16 Jul 2015, Julien Grall wrote: > Hi Stefano, > > On 16/07/2015 16:43, Stefano Stabellini wrote: > > On Thu, 9 Jul 2015, 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: > > ^ waste > > > > > * 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. > > > > But this is not implemented in this series, right? > > Yes, it's some ideas to improve the code. > > > > > > > > Signed-off-by: Julien Grall > > > Cc: Konrad Rzeszutek Wilk > > > Cc: Boris Ostrovsky > > > Cc: David Vrabel > > > --- > > > drivers/xen/events/events_base.c | 2 +- > > > drivers/xen/events/events_fifo.c | 2 +- > > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/xen/events/events_base.c > > > b/drivers/xen/events/events_base.c > > > index 96093ae..858d2f6 100644 > > > --- a/drivers/xen/events/events_base.c > > > +++ b/drivers/xen/events/events_base.c > > > @@ -40,11 +40,11 @@ > > > #include > > > #include > > > #include > > > -#include > > > #endif > > > #include > > > #include > > > #include > > > +#include > > > > > > #include > > > #include > > > > Spurious change? > > No, xen/page.h was only included for x86 before. Now, it's included for every > architecture. > > This is required in order to get XEN_PAGE_SIZE. Ah, right. Reviewed-by: Stefano Stabellini -- 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/