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Fri, 27 Aug 2021 20:06:20 -0400 (EDT) Received: from mail03.efficios.com (mail03.efficios.com [167.114.26.124]) by mail.efficios.com (Postfix) with ESMTP id 87F07383C99; Fri, 27 Aug 2021 20:06:20 -0400 (EDT) Date: Fri, 27 Aug 2021 20:06:20 -0400 (EDT) From: Mathieu Desnoyers To: Sean Christopherson Cc: dvhart , "Russell King, ARM Linux" , Catalin Marinas , Will Deacon , Guo Ren , Thomas Bogendoerfer , Michael Ellerman , Heiko Carstens , gor , Christian Borntraeger , rostedt , Ingo Molnar , Oleg Nesterov , Thomas Gleixner , Peter Zijlstra , Andy Lutomirski , paulmck , Boqun Feng , Paolo Bonzini , shuah , Benjamin Herrenschmidt , Paul Mackerras , linux-arm-kernel , linux-kernel , linux-csky , linux-mips , linuxppc-dev , linux-s390 , KVM list , linux-kselftest , Peter Foley , Shakeel Butt , Ben Gardon Message-ID: <1054916754.30218.1630109180443.JavaMail.zimbra@efficios.com> In-Reply-To: References: <20210820225002.310652-1-seanjc@google.com> <766990430.21713.1629731934069.JavaMail.zimbra@efficios.com> <282257549.21721.1629732017655.JavaMail.zimbra@efficios.com> <1700758714.29394.1630003332081.JavaMail.zimbra@efficios.com> <339641531.29941.1630091374065.JavaMail.zimbra@efficios.com> Subject: Re: [PATCH v2 4/5] KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs MIME-Version: 1.0 X-Originating-IP: [167.114.26.124] X-Mailer: Zimbra 8.8.15_GA_4101 (ZimbraWebClient - FF91 (Linux)/8.8.15_GA_4059) Thread-Topic: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs Thread-Index: eu98ugrRMaO1Ldp5KUn1lSy5MLrp5Q== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210827_170627_828398_09050C55 X-CRM114-Status: UNSURE ( 8.46 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org ----- On Aug 27, 2021, at 7:23 PM, Sean Christopherson seanjc@google.com wrote: > On Fri, Aug 27, 2021, Mathieu Desnoyers wrote: [...] >> Does it reproduce if we randomize the delay to have it picked randomly from 0us >> to 100us (with 1us step) ? It would remove a lot of the needs for arch-specific >> magic delay value. > > My less-than-scientific testing shows that it can reproduce at delays up to > ~500us, > but above ~10us the reproducibility starts to drop. The bug still reproduces > reliably, it just takes more iterations, and obviously the test runs a bit > slower. > > Any objection to using a 1-10us delay, e.g. a simple usleep((i % 10) + 1)? Works for me, thanks! Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel