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That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: QEMU Developers , robhenry@microsoft.com, aaron@os.amperecomputing.com, "Emilio G. Cota" , kuhn.chenqun@huawei.com, Peter Puhov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Robert Foley writes: > On Wed, 3 Jun 2020 at 07:43, Alex Benn=C3=A9e wr= ote: >> >> >> Robert Foley writes: >> > >> > >> > When testing out the options, I noticed that >> > if we supply arguments of "read", and "write", then we will only get >> > the last one set, "write", since rw gets overwritten. >> > One option would be to error out if more than one of these read/write >> > args is supplied. >> >> Yeah the option parsing is a little clunky although given the way you >> pass them from the QEMU command line perhaps not too worth finessing. >> The default is rw so you make a conscious decision to only care about one >> or the other. >> >> All you can really do is fail to initialise the plugin. Hopefully the >> output should be enough clue. >> >> > >> > Reviewed-by: Robert Foley >> > Tested-by: Robert Foley >> >> Thanks. >> >> Out of interest what did you measure? Are there any useful use cases you= can >> think of? > > We did some testing where we booted an aarch64 VM and an i386 VM a few ti= mes > with differentcore counts (up to 64), and viewed the counters. We > also did a test where > we inserted another device (a virtfs mount), booted up and checked > that there was another > device listed (for virtio-9p). > > There are a few useful use cases we are thinking of, in general for debug= /perf > testing of PCI devices/drivers. > For example, debug and performance test of a case where we use a queue pa= ir, > (maybe for something like DPDK/SPDK), this plugin would be interesting for > checking that the quantity and locations of accesses are expected. So one thing that has come up in the VIRT-366 discussion is the potential efficiencies of the various kick models for MMIO based hypervisors. Each interaction with a trapped region of memory triggers a vmexit and one thing I wanted to understand for example was the difference between "normal" IRQs and MSIs. --=20 Alex Benn=C3=A9e