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Wed, 10 Jul 2024 05:09:49 -0400 (EDT) Date: Wed, 10 Jul 2024 11:09:43 +0200 From: Klaus Jensen To: Keith Busch Cc: Ayush Mishra , qemu-devel@nongnu.org, foss@defmacro.it Subject: Re: [PATCH] hw/nvme: actually implement abort Message-ID: References: <20240702080232.848849-1-ayush.m55@samsung.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="MMwpjxQe2z0AZVYP" Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=103.168.172.148; envelope-from=its@irrelevant.dk; helo=fout5-smtp.messagingengine.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --MMwpjxQe2z0AZVYP Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Jul 2 20:55, Klaus Jensen wrote: > On Jul 2 09:24, Keith Busch wrote: > > On Tue, Jul 02, 2024 at 01:32:32PM +0530, Ayush Mishra wrote: > > > Abort was not implemented previously, but we can implement it for AER= s and asynchrnously for I/O. > >=20 > > Not implemented for a reason. The target has no idea if the CID the > > host requested to be aborted is from the same context that the target > > has. Target may have previoulsy completed it, and the host re-issued a > > new command after the abort, and due to the queueing could have been > > observed in a different order, and now you aborted the wrong command. >=20 > I might be missing something here, but are you saying that the Abort > command is fundamentally flawed? Isn't this a host issue? The Abort is > for a specific CID on a specific SQID. The host *should* not screw this > up and reuse a CID it has an outstanding Abort on? >=20 > I don't think there are a lot of I/O commands that a host would be able > to cancel (in QEMU, not at all, because only the iscsi backend > actually implements blk_aio_cancel_async). But some commands that issue > multiple AIOs, like Copy, may be long running and with this it can > actually be cancelled. >=20 > And with regards to AERs, I don't see why it is not advantageous to be > able to Abort one? Keith, any thoughts on this? --MMwpjxQe2z0AZVYP Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEUigzqnXi3OaiR2bATeGvMW1PDekFAmaOT9cACgkQTeGvMW1P DekgSgf+LqM7ajy4xipZeGqf/koC4JZ1ql+56iCGqb2xZaKddLDtrnWFuTUcwN7S 4IxEudzWbqq++zZXV/pzflxcXWAdd7P3uMgo259p2hSmieATerFZdoi+oB+UpuDV svCgMStmCrusJTnvbszLluXnTzBDobPACMb7EVUSkL3YKA30Fp4VOdHQrS1gEg7L Ee9xJ1Qcc0Z0L7CvZRSuZD7S/4/iOGW3nfn5Ljdrxz6UVpDD8ZmMy4/vMkJN9Yf5 3CB/mES9dM4JPbdDgCuBKEAQt52o8CWUZtQpHufO87CeT8QJ9N7umTFzJSorfvgj IvebBdBii6L1cQlmPsvsYHTDcIvBfw== =9URF -----END PGP SIGNATURE----- --MMwpjxQe2z0AZVYP--