From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DC8DC004D3 for ; Tue, 23 Oct 2018 03:00:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17C6220665 for ; Tue, 23 Oct 2018 03:00:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17C6220665 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727313AbeJWLVs (ORCPT ); Tue, 23 Oct 2018 07:21:48 -0400 Received: from mga02.intel.com ([134.134.136.20]:36021 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726438AbeJWLVr (ORCPT ); Tue, 23 Oct 2018 07:21:47 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Oct 2018 20:00:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,414,1534834800"; d="scan'208";a="83353089" Received: from yisun1-ubuntu.bj.intel.com (HELO localhost) ([10.238.156.104]) by orsmga007.jf.intel.com with ESMTP; 22 Oct 2018 20:00:24 -0700 Date: Tue, 23 Oct 2018 10:57:40 +0800 From: Yi Sun To: Peter Zijlstra Cc: Waiman Long , Juergen Gross , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, chao.p.peng@intel.com, chao.gao@intel.com, isaku.yamahata@intel.com, michael.h.kelley@microsoft.com, tianyu.lan@microsoft.com, "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , "mingo@redhat.com" , Will Deacon Subject: Re: [PATCH v1 2/2] x86/hyperv: make HvNotifyLongSpinWait hypercall Message-ID: <20181023025740.GL11769@yi.y.sun> References: <1539954835-34035-1-git-send-email-yi.y.sun@linux.intel.com> <1539954835-34035-3-git-send-email-yi.y.sun@linux.intel.com> <20181022015342.GK11769@yi.y.sun> <2e0d62cb-b706-a5b4-65f7-982a913fb32b@suse.com> <20181022171516.GH3117@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181022171516.GH3117@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18-10-22 19:15:16, Peter Zijlstra wrote: > > Firstly, who come a patch that is grubbing around in kernel/locking/ has > an x86/hyperv subject and isn't Cc'ed to the locking maintainers? > I am sorry. That is my fault to forget to add locking maintainers. > On Mon, Oct 22, 2018 at 12:31:45PM -0400, Waiman Long wrote: > > On 10/22/2018 03:32 AM, Juergen Gross wrote: > > > On 22/10/2018 03:53, Yi Sun wrote: > > >> On 18-10-19 16:20:52, Juergen Gross wrote: > > >>> On 19/10/2018 15:13, Yi Sun wrote: > > >> [...] > > >> > > >>>> diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h > > >>>> index 0130e48..9e88c7e 100644 > > >>>> --- a/kernel/locking/qspinlock_paravirt.h > > >>>> +++ b/kernel/locking/qspinlock_paravirt.h > > >>>> @@ -7,6 +7,8 @@ > > >>>> #include > > >>>> #include > > >>>> > > >>>> +#include > > >>>> + > > >>>> /* > > >>>> * Implement paravirt qspinlocks; the general idea is to halt the vcpus instead > > >>>> * of spinning them. > > >>>> @@ -305,6 +307,10 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) > > >>>> wait_early = true; > > >>>> break; > > >>>> } > > >>>> +#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS) && IS_ENABLED(CONFIG_HYPERV) > > >>>> + if (!hv_notify_long_spin_wait(SPIN_THRESHOLD - loop)) > > >>>> + break; > > >>>> +#endif > > Secondly; how come you thought that was acceptable in any way shape or > form? > Sorry for that. Will try another way. > > > vcpu_is_preempted() is already part of this loop. And this is a paravirt > > > hook. Can't you make use of that? This might require adding another > > > parameter to this hook, but I'd prefer that over another pv-spinlock > > > hook. > > > I agree with Juergen on that. I would suggest rename the > > vcpu_is_preempted hook into a more generic vcpu_stop_spinning, perhaps, > > so different hypervisors can act on the information accordingly. Adding > > an extra parameter is fine. > > No; no extra parameters. vcpu_is_preempted() is a simple and intuitive > interface. Why would we want to make it complicated?