From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759729Ab0JZOuO (ORCPT ); Tue, 26 Oct 2010 10:50:14 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:2153 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751796Ab0JZOuM (ORCPT ); Tue, 26 Oct 2010 10:50:12 -0400 X-IronPort-AV: E=Sophos;i="4.58,241,1286164800"; d="scan'208";a="119745268" Subject: Re: [PATCH 5/5] xen: events: use per-cpu variable for cpu_evtchn_mask From: Ian Campbell To: Konrad Rzeszutek Wilk CC: Jeremy Fitzhardinge , Stefano Stabellini , "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , "mingo@elte.hu" , "xen-devel@lists.xensource.com" , "tglx@linutronix.de" In-Reply-To: <20101026143615.GD9557@dumpdata.com> References: <1288023736.11153.40.camel@zakaz.uk.xensource.com> <1288023813-31989-5-git-send-email-ian.campbell@citrix.com> <20101026143615.GD9557@dumpdata.com> Content-Type: text/plain; charset="UTF-8" Organization: Citrix Systems, Inc. Date: Tue, 26 Oct 2010 15:50:08 +0100 Message-ID: <1288104608.8361.15.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-10-26 at 15:36 +0100, Konrad Rzeszutek Wilk wrote: > On Mon, Oct 25, 2010 at 05:23:33PM +0100, Ian Campbell wrote: > > I can't see any reason why it isn't already. > > > > Signed-off-by: Ian Campbell > > --- > > drivers/xen/events.c | 31 +++++++++++-------------------- > > 1 files changed, 11 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/xen/events.c b/drivers/xen/events.c > > index 9b58505..144ff72 100644 > > --- a/drivers/xen/events.c > > +++ b/drivers/xen/events.c > > @@ -110,19 +110,9 @@ static int *pirq_to_irq; > > static int nr_pirqs; > > > > static int *evtchn_to_irq; > > -struct cpu_evtchn_s { > > - unsigned long bits[NR_EVENT_CHANNELS/BITS_PER_LONG]; > > -}; > > > > -static __initdata struct cpu_evtchn_s init_evtchn_mask = { > > - .bits[0 ... (NR_EVENT_CHANNELS/BITS_PER_LONG)-1] = ~0ul, > > -}; > > -static struct cpu_evtchn_s *cpu_evtchn_mask_p = &init_evtchn_mask; > > - > > -static inline unsigned long *cpu_evtchn_mask(int cpu) > > -{ > > - return cpu_evtchn_mask_p[cpu].bits; > > -} > > +static DEFINE_PER_CPU(unsigned long [NR_EVENT_CHANNELS/BITS_PER_LONG], > > + cpu_evtchn_mask); > > > > /* Xen will never allocate port zero for any purpose. */ > > #define VALID_EVTCHN(chn) ((chn) != 0) > > @@ -301,7 +291,7 @@ static inline unsigned long active_evtchns(unsigned int cpu, > > unsigned int idx) > > { > > return (sh->evtchn_pending[idx] & > > - cpu_evtchn_mask(cpu)[idx] & > > + per_cpu(cpu_evtchn_mask, cpu)[idx] & > > ~sh->evtchn_mask[idx]); > > } > > > > @@ -314,8 +304,8 @@ static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu) > > cpumask_copy(irq_to_desc(irq)->affinity, cpumask_of(cpu)); > > #endif > > > > - __clear_bit(chn, cpu_evtchn_mask(cpu_from_irq(irq))); > > - __set_bit(chn, cpu_evtchn_mask(cpu)); > > + __clear_bit(chn, per_cpu(cpu_evtchn_mask, cpu_from_irq(irq))); > > + __set_bit(chn, per_cpu(cpu_evtchn_mask, cpu)); > > > > info_for_irq(irq)->cpu = cpu; > > } > > @@ -332,7 +322,11 @@ static void init_evtchn_cpu_bindings(void) > > } > > #endif > > > > - memset(cpu_evtchn_mask(0), ~0, sizeof(struct cpu_evtchn_s)); > > + printk(KERN_CRIT "%s: CPU0 at %p size %zd\n", __func__, > > If this is per_cpu, wouldn't the comment 'CPU0 at' be improper? Oops, that was just debug anyway. > Hmm, so we use percpu structure, but all of the event channel and such > are set for CPU0. So what is the benefit of this, when the interrupts > are _only_ happening on CPU0? All event channels start off bound to VCPU0 so we need to initialise cpu_evtchn_mask(0) to have all ones and leave all the other CPU's bitmaps with all zeros. > Oh, right, there is also the rebind cpu function somewhere so that the > spinlock, timers, etc are allocated on other CPUs, right? All evtchn's start off bound to VCPU 0 but the kernel can rebind as necessary. Ian.