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([2001:b07:6468:f312:f43b:97b2:4c89:7446]) by smtp.gmail.com with ESMTPSA id 5sm4473852wmg.34.2020.04.21.12.52.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Apr 2020 12:52:48 -0700 (PDT) Subject: Re: [PATCH v2] kvm: Replace vcpu->swait with rcuwait To: Davidlohr Bueso Cc: Marc Zyngier , tglx@linutronix.de, kvm@vger.kernel.org, Davidlohr Bueso , peterz@infradead.org, torvalds@linux-foundation.org, bigeasy@linutronix.de, linux-kernel@vger.kernel.org, rostedt@goodmis.org, linux-mips@vger.kernel.org, Paul Mackerras , joel@joelfernandes.org, will@kernel.org, kvmarm@lists.cs.columbia.edu References: <20200324044453.15733-1-dave@stgolabs.net> <20200324044453.15733-4-dave@stgolabs.net> <20200420164132.tjzk5ebx35m66yce@linux-p48b> <418acdb5001a9ae836095b7187338085@misterjones.org> <20200420205641.6sgsllj6pmsnwrvp@linux-p48b> <20200420215014.sarodevmhphnkkn7@linux-p48b> <02e1b00d-a8ea-a947-bbe6-0b1380aa7ec4@redhat.com> <20200421180733.xrl5ta6cuo2weuva@linux-p48b> From: Paolo Bonzini Message-ID: Date: Tue, 21 Apr 2020 21:52:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200421180733.xrl5ta6cuo2weuva@linux-p48b> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 21/04/20 20:07, Davidlohr Bueso wrote: >> > > I should have looked closer here - I was thinking about the return > value of rcuwait_wait_event. Yes, that signal_pending check you > mention makes the sleep semantics change bogus as interruptible is no > longer just to avoid contributing to the load balance. > > And yes, unfortunately adding prepare_to and finish_rcuwait() looks > like the most reasonable approach to keeping the tracepoint > semantics. I also considered extending rcuwait_wait_event() by > another parameter to pass back to the caller if there was any wait at > all, but that enlarges the call and is probably less generic. Yes, at some point the usual prepare_to/finish APIs become simpler. > I'll send another version keeping the current sleep and tracepoint > semantics. Thanks---and sorry, I should have noticed that way earlier. Paolo