From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Qemu-devel] [RFC] create a single workqueue for each vm to update vm irq routing table Date: Thu, 28 Nov 2013 13:33:17 +0200 Message-ID: <529729FD.3030901@cloudius-systems.com> References: <5294BC3B.6070902@redhat.com> <5297050E.6000700@redhat.com> <20131128091903.GA4609@kernel.org> <5297118C.3050104@cloudius-systems.com> <529712A1.8090207@redhat.com> <5297181B.3090109@cloudius-systems.com> <52971D86.60601@redhat.com> <20131128110915.GD5822@minantech.com> <529724B0.80405@redhat.com> <20131128112348.GF5822@minantech.com> <52972991.1050407@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Zhanghaoyu (A)" , Gleb Natapov , Avi Kivity , "Huangweidong (C)" , KVM , "Michael S. Tsirkin" , "Jinxin (F)" , Luonengjun , "qemu-devel@nongnu.org" , Zanghongyong To: Paolo Bonzini , Gleb Natapov Return-path: Received: from mail-bk0-f48.google.com ([209.85.214.48]:42915 "EHLO mail-bk0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758093Ab3K1LdW (ORCPT ); Thu, 28 Nov 2013 06:33:22 -0500 Received: by mail-bk0-f48.google.com with SMTP id v10so3704543bkz.21 for ; Thu, 28 Nov 2013 03:33:21 -0800 (PST) In-Reply-To: <52972991.1050407@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 11/28/2013 01:31 PM, Paolo Bonzini wrote: > Il 28/11/2013 12:23, Gleb Natapov ha scritto: >>>>>> Unless what ? :) Unless reader is scheduled out? >>>> Yes. Or unless my brain is scheduled out in the middle of a sentence. >>>> >> So we will have to disable preemption in a reader to prevent big latencies for >> a writer, no? > I don't think that's necessary. The writer itself could also be > scheduled out, and the reader critical sections are really small. Let's > wait for Zhang to try SRCU and report back. > I think readers have preemption disabled already in that context (irqfd writes).