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([2001:b07:6468:f312:7841:78cc:18c6:1e20]) by smtp.gmail.com with ESMTPSA id d14sm29180357wre.44.2020.08.04.01.23.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Aug 2020 01:23:42 -0700 (PDT) Subject: Re: [RFC v3 1/8] cpu-timers, icount: new modules To: Claudio Fontana , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Peter Maydell , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Pavel Dovgalyuk References: <20200803090533.7410-1-cfontana@suse.de> <20200803090533.7410-2-cfontana@suse.de> <910286a7-805d-3b62-a3b0-aeb5d0a9606e@suse.de> From: Paolo Bonzini Message-ID: <5b34dad3-9868-c773-4ce0-0063837e17a2@redhat.com> Date: Tue, 4 Aug 2020 10:23:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <910286a7-805d-3b62-a3b0-aeb5d0a9606e@suse.de> Content-Language: en-US X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=205.139.110.61; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/04 01:28:16 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Thomas Huth , Eduardo Habkost , Marcelo Tosatti , Markus Armbruster , qemu-devel@nongnu.org, Roman Bolshakov , haxm-team@intel.com, Wenchao Wang , Sunil Muthuswamy , Richard Henderson , Colin Xu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 04/08/20 10:13, Claudio Fontana wrote: >> - if (mem && use_icount && dbs->dir == DMA_DIRECTION_FROM_DEVICE) { >> + if (mem && icount_enabled() && dbs->dir == DMA_DIRECTION_FROM_DEVICE) { > > > > In this specific case, where dma_blk_cb() changes its behaviour to be more deterministic > if icount_enabled(), > > do you think that if qtest_enabled() we should also follow the more deterministic path, > or should we go through the "normal" path instead, as this patch does? > > Tests pass in any case, but I wonder what would be the best behavior for qtest accel in this case. > (Maybe Pavel?) No, qtests simply should not use SG lists that cause the problematic nondeterminism. We don't have that luxury for guests. Paolo