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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 30F6EC4332B for ; Sun, 22 Mar 2020 16:34:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C8EA20724 for ; Sun, 22 Mar 2020 16:34:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726666AbgCVQe2 (ORCPT ); Sun, 22 Mar 2020 12:34:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:52958 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726502AbgCVQe2 (ORCPT ); Sun, 22 Mar 2020 12:34:28 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 93574AC24; Sun, 22 Mar 2020 16:34:24 +0000 (UTC) Date: Sun, 22 Mar 2020 09:33:17 -0700 From: Davidlohr Bueso To: Peter Zijlstra Cc: tglx@linutronix.de, arnd@arndb.de, balbi@kernel.org, bhelgaas@google.com, bigeasy@linutronix.de, davem@davemloft.net, gregkh@linuxfoundation.org, joel@joelfernandes.org, kurt.schwemmer@microsemi.com, kvalo@codeaurora.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, logang@deltatee.com, mingo@kernel.org, mpe@ellerman.id.au, netdev@vger.kernel.org, oleg@redhat.com, paulmck@kernel.org, rdunlap@infradead.org, rostedt@goodmis.org, torvalds@linux-foundation.org, will@kernel.org, Paolo Bonzini , Davidlohr Bueso Subject: Re: [PATCH 18/15] kvm: Replace vcpu->swait with rcuwait Message-ID: <20200322163317.mh4sygr7xcjptmjp@linux-p48b> References: <20200318204302.693307984@linutronix.de> <20200320085527.23861-1-dave@stgolabs.net> <20200320085527.23861-3-dave@stgolabs.net> <20200320125455.GE20696@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200320125455.GE20696@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20180716 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Fri, 20 Mar 2020, Peter Zijlstra wrote: >On Fri, Mar 20, 2020 at 01:55:26AM -0700, Davidlohr Bueso wrote: >> - swait_event_interruptible_exclusive(*wq, ((!vcpu->arch.power_off) && >> - (!vcpu->arch.pause))); >> + rcuwait_wait_event(*wait, >> + (!vcpu->arch.power_off) && (!vcpu->arch.pause), >> + TASK_INTERRUPTIBLE); > >> - for (;;) { >> - prepare_to_swait_exclusive(&vcpu->wq, &wait, TASK_INTERRUPTIBLE); >> - >> - if (kvm_vcpu_check_block(vcpu) < 0) >> - break; >> - >> - waited = true; >> - schedule(); >> - } >> - >> - finish_swait(&vcpu->wq, &wait); >> + rcuwait_wait_event(&vcpu->wait, >> + (block_check = kvm_vcpu_check_block(vcpu)) < 0, >> + TASK_INTERRUPTIBLE); > >Are these yet more instances that really want to be TASK_IDLE ? Hmm probably as it makes sense for a blocked vcpu not to be contributing to the loadavg. So if this is the only reason to use interruptible, then yes we ought to change it. However, I'll make this a separate patch, given this (ab)use isn't as obvious as the PS3 case, which is a kthread and therefore signals are masked. Thanks, Davidlohr