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Tsirkin" To: Gerd Hoffmann Subject: Re: [PATCH 0/6] RfC: try improve native hotplug for pcie root ports Message-ID: <20211019014209-mutt-send-email-mst@kernel.org> References: <20211011120504.254053-1-kraxel@redhat.com> <20211018113535-mutt-send-email-mst@kernel.org> <20211019052144.q4cy2qrvdh34rxml@sirius.home.kraxel.org> MIME-Version: 1.0 In-Reply-To: <20211019052144.q4cy2qrvdh34rxml@sirius.home.kraxel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.049, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, 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: Paolo Bonzini , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Oct 19, 2021 at 07:21:44AM +0200, Gerd Hoffmann wrote: > On Mon, Oct 18, 2021 at 11:36:45AM -0400, Michael S. Tsirkin wrote: > > On Mon, Oct 11, 2021 at 02:04:58PM +0200, Gerd Hoffmann wrote: > > > > > > > > > Gerd Hoffmann (6): > > > pci: implement power state > > > pcie: implement slow power control for pcie root ports > > > pcie: add power indicator blink check > > > pcie: factor out pcie_cap_slot_unplug() > > > pcie: fast unplug when slot power is off > > > pcie: expire pending delete > > > > So what's left to do here? > > I'm guessing more testing? > > Yes. Maybe ask rh qe to run the patch set through their hotplug test > suite (to avoid a apci-hotplug style disaster where qe found various > issues after release)? I'll poke around to see if they can help us... we'll need a backport for that though. > > I would also like to see a shorter timeout, maybe 100ms, so > > that we are more responsive to guest changes in resending request. > > I don't think it is a good idea to go for a shorter timeout given that > the 5 seconds are in the specs and we want avoid a resent request being > interpreted as cancel. > It also wouldn't change anything at least for linux guests because linux > is waiting those 5 seconds (with power indicator in blinking state). > Only the reason for refusing 'device_del' changes from "5 secs not over > yet" to "guest is busy processing the hotplug request". First 5 seconds yes. But the retries afterwards? > > We could consider to tackle the 5sec timeout on the guest side, i.e. > have linux skip the 5sec wait in case the root port is virtual (should > be easy to figure by checking the pci id). > > take care, > Gerd Yes ... do we want to control how long it blinks from hypervisor side? And if we do then what? Shorten retry period? -- MST