Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932171AbbGPPoM (ORCPT ); Thu, 16 Jul 2015 11:44:12 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:56430 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752015AbbGPPoJ (ORCPT ); Thu, 16 Jul 2015 11:44:09 -0400 X-IronPort-AV: E=Sophos;i="5.15,488,1432598400"; d="scan'208";a="284770950" Date: Thu, 16 Jul 2015 16:43:04 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Julien Grall CC: , , , , , Konrad Rzeszutek Wilk , Boris Ostrovsky , "David Vrabel" Subject: Re: [PATCH v2 13/20] xen/events: fifo: Make it running on 64KB granularity In-Reply-To: <1436474552-31789-14-git-send-email-julien.grall@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> 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: 2491 Lines: 72 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? > 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? > diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c > index ed673e1..d53c297 100644 > --- a/drivers/xen/events/events_fifo.c > +++ b/drivers/xen/events/events_fifo.c > @@ -54,7 +54,7 @@ > > #include "events_internal.h" > > -#define EVENT_WORDS_PER_PAGE (PAGE_SIZE / sizeof(event_word_t)) > +#define EVENT_WORDS_PER_PAGE (XEN_PAGE_SIZE / sizeof(event_word_t)) > #define MAX_EVENT_ARRAY_PAGES (EVTCHN_FIFO_NR_CHANNELS / EVENT_WORDS_PER_PAGE) > > struct evtchn_fifo_queue { > -- > 2.1.4 > -- 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/