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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 74F94C432BE for ; Sat, 28 Aug 2021 00:06:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C4DC60F92 for ; Sat, 28 Aug 2021 00:06:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232732AbhH1AHY (ORCPT ); Fri, 27 Aug 2021 20:07:24 -0400 Received: from mail.efficios.com ([167.114.26.124]:47366 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232558AbhH1AHP (ORCPT ); Fri, 27 Aug 2021 20:07:15 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 334D2383D90; Fri, 27 Aug 2021 20:06:25 -0400 (EDT) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id dJnw97AVp-6J; Fri, 27 Aug 2021 20:06:20 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id AABF53839D9; Fri, 27 Aug 2021 20:06:20 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com AABF53839D9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1630109180; bh=aNbnUoaMo9qyJFeAmPDlGUugMe1xHV+lzHQym41zPgk=; h=Date:From:To:Message-ID:MIME-Version; b=ibXqVy9zMTh8pzWhCDOoh0A6j0FvWS8eYDH852Q65ZQn7p1jJGIre5/cPOpdeIP+y aA3o07Eg6BWPXmQhKAcL/ut69D3yBdvdejeJXIhzPTSWYfZet9c55De2zXu/+jv9qb 9rMBUNtRH3XFmY4l5818jP7JeOTnYOyaVW6g21SlH6hM5lnPmcjj7mBKimFhzIieoI r/xa04WF8N3Rq/3K+SW2ss83aevuy6/MvU/Sy30Y15mPyUw7HSYrNN1GbX2+DRw0YH 7ZItjz+GSSq3DkuqubXPIjIIupZU9sNhSleF8+cDrSh10TSYD5CLywa6jmXG5NyjL6 CV8mJ14ojbACA== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 9JJ04Y5MGhgL; 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 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit 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== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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