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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 039BCC433F4 for ; Tue, 28 Aug 2018 20:59:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5A4B20847 for ; Tue, 28 Aug 2018 20:59:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B5A4B20847 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 S1727467AbeH2AxR (ORCPT ); Tue, 28 Aug 2018 20:53:17 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58516 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726383AbeH2AxR (ORCPT ); Tue, 28 Aug 2018 20:53:17 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DDF54401EF04; Tue, 28 Aug 2018 20:59:51 +0000 (UTC) Received: from vitty.brq.redhat.com.redhat.com (ovpn-204-130.brq.redhat.com [10.40.204.130]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F3F1A2026D6B; Tue, 28 Aug 2018 20:59:48 +0000 (UTC) From: Vitaly Kuznetsov To: "Michael Kelley \(EOSG\)" Cc: "mhkelley58\@gmail.com" , "gregkh\@linuxfoundation.org" , "linux-kernel\@vger.kernel.org" , "devel\@linuxdriverproject.org" , "olaf\@aepfle.de" , "apw\@canonical.com" , "jasowang\@redhat.com" , "marcelo.cerri\@canonical.com" , Stephen Hemminger , KY Srinivasan Subject: Re: [PATCH char-misc 1/1] Drivers: hv: vmbus: Make synic_initialized flag per-cpu References: <1533004484-3937-1-git-send-email-mikelley@microsoft.com> <87ftzzodnv.fsf@vitty.brq.redhat.com> <8736vyo2tm.fsf@vitty.brq.redhat.com> Date: Tue, 28 Aug 2018 22:59:47 +0200 In-Reply-To: (Michael Kelley's message of "Tue, 28 Aug 2018 20:20:19 +0000") Message-ID: <87va7uxl4s.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Tue, 28 Aug 2018 20:59:51 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Tue, 28 Aug 2018 20:59:51 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'vkuznets@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Michael Kelley (EOSG)" writes: > From: Vitaly Kuznetsov Sent: Wednesday, August 1, 2018 2:26 AM > >> > I was trying to decide if there are any arguments in favor of one >> > approach vs. the other: a per-cpu flag in memory or checking >> > the synic_control "enable" bit. Seems like a wash to me, in which >> > case I have a slight preference for the per-cpu flag in memory vs. >> > creating another function to return sctrl.enable. But I'm completely >> > open to reasons why checking sctrl.enable is better. >> >> Just a few thoughts: reading MSR is definitely slower but we avoid >> 'shadowing' the state, the reading is always correct. In case there's a >> chance the SynIC will get disabled from host side we can only find this >> out by doing MSR read. This is a purely theoretical possibility, I >> believe, we can go ahead with this patch. > > Vitaly -- just to confirm: you are OK with the patch as is? (I'll > check, but I may need to rebase on the latest code.) Yes, feel free to use my R-b tag. -- Vitaly