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Thu, 14 Jul 2022 17:24:49 +0900 (KST) Received: from epsmtrp1.samsung.com (unknown [182.195.40.13]) by epcas5p1.samsung.com (KnoxPortal) with ESMTPA id 20220714082448epcas5p1a3497e7ce59fe8b5388afe8c3edfc6d0~BpJLdb9vS1554115541epcas5p1J; Thu, 14 Jul 2022 08:24:48 +0000 (GMT) Received: from epsmgms1p2.samsung.com (unknown [182.195.42.42]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20220714082448epsmtrp1df67c0bc5028944645406faa6e3d15d9~BpJLcozEi0497104971epsmtrp1e; Thu, 14 Jul 2022 08:24:48 +0000 (GMT) X-AuditID: b6c32a4a-b8dff7000000255e-ab-62cfd2d19600 Received: from epsmtip1.samsung.com ( [182.195.34.30]) by epsmgms1p2.samsung.com (Symantec Messaging Gateway) with SMTP id BB.98.08802.0D2DFC26; Thu, 14 Jul 2022 17:24:48 +0900 (KST) Received: from test-zns (unknown [107.110.206.5]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20220714082446epsmtip1e51819c52649a216baff5f9dfc1b9ef1~BpJJrUxNX0771807718epsmtip1f; Thu, 14 Jul 2022 08:24:46 +0000 (GMT) Date: Thu, 14 Jul 2022 13:49:23 +0530 From: Kanchan Joshi To: Ming Lei Cc: Sagi Grimberg , Jens Axboe , hch@lst.de, kbusch@kernel.org, io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, asml.silence@gmail.com, joshiiitr@gmail.com, anuj20.g@samsung.com, gost.dev@samsung.com Subject: Re: [PATCH for-next 3/4] io_uring: grow a field in struct io_uring_cmd Message-ID: <20220714081923.GE30733@test-zns> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrGJsWRmVeSWpSXmKPExsWy7bCmlu7FS+eTDBpv81s0TfjLbDFn1TZG i9V3+9ksbh7YyWSxcvVRJot3redYLM6/PcxkMenQNUaLvbe0LeYve8pucWhyM5PFutfvWRx4 PHbOusvucf7eRhaPy2dLPTat6mTz2Lyk3mP3zQY2j/f7rrJ59G1ZxejxeZNcAGdUtk1GamJK apFCal5yfkpmXrqtkndwvHO8qZmBoa6hpYW5kkJeYm6qrZKLT4CuW2YO0MFKCmWJOaVAoYDE 4mIlfTubovzSklSFjPziElul1IKUnAKTAr3ixNzi0rx0vbzUEitDAwMjU6DChOyMNcf4Cnbz V9y9tIm5gfEWTxcjJ4eEgInE8mVnGUFsIYHdjBJHFud1MXIB2Z8YJV43LmSDcD4zSiyZfZMZ puPW/amMEIldjBLz/r1mh3CeMUosvvKAtYuRg4NFQFWiZbERiMkmoClxYXIpSK+IgJLE3bur 2UFsZoGZTBJvOpVBbGGBQInVvXvA4rwCuhKb71+FsgUlTs58wgJicwqoSLRuXwB2qaiAssSB bceZQNZKCOzgkJj/fC8TxHEuElfm74OyhSVeHd/CDmFLSbzsb4OykyUuzTwHVVMi8XjPQSjb XqL1VD8zxHGZEotX3WGBsPkken8/YQL5RUKAV6KjTQiiXFHi3qSnrBC2uMTDGUugbA+Jm7f2 QgPuE5PEuclLWScwys1C8s8sJCsgbCuJzg9NrLOAVjALSEss/8cBYWpKrN+lv4CRdRWjZGpB cW56arFpgVFeajk8hpPzczcxghOwltcOxocPPugdYmTiYDzEKMHBrCTC233oXJIQb0piZVVq UX58UWlOavEhRlNg7ExklhJNzgfmgLySeEMTSwMTMzMzE0tjM0MlcV6vq5uShATSE0tSs1NT C1KLYPqYODilGphC/ryosVxZNvdD1ezfq9ccPRRwlqM+b+fXfK47U+64y6q7bYy9Jath8uAB B+NvMV82F8HIbUbfJge84c9J1pm+ee3OS7NXbtux5cZ7mwP73M3vsywWfOWn9cbr1I4bn+cy S0ZPu9y0ocil+O3/mf9PqN/+naZktcO4V+2eMNOxmVskE5fm/Jr9zvmgYZXm//89Cc1rj4gZ GvIvP1fK9rpZd6Nu/yPF7znioo2RZ0vuLLu+xJWht1ae3dquoGLu3qZNX+xn3ZhU6q7Be5Rx 9eObDp/1IgLFpERC1a4w9us/ntM/4frehLDb5h99Zs38O2cKw1GV7eeFF7hZTJO45RgVI3PZ dqF0T6lG+911jT91lViKMxINtZiLihMBqxB5VUkEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmphkeLIzCtJLcpLzFFi42LZdlhJTvfCpfNJBts3Slo0TfjLbDFn1TZG i9V3+9ksbh7YyWSxcvVRJot3redYLM6/PcxkMenQNUaLvbe0LeYve8pucWhyM5PFutfvWRx4 PHbOusvucf7eRhaPy2dLPTat6mTz2Lyk3mP3zQY2j/f7rrJ59G1ZxejxeZNcAGcUl01Kak5m WWqRvl0CV8aT5p3sBa94Kh7tXcvUwLiYq4uRk0NCwETi1v2pjCC2kMAORonL19Ih4uISzdd+ sEPYwhIr/z0HsrmAap4wSqzfsIG1i5GDg0VAVaJlsRGIySagKXFhcilIuYiAksTdu6vBWpkF ZjJJvOlUBrGFBQIlVvfuAYvzCuhKbL5/lR1i7RcmienLXSDighInZz5hgeg1k5i3+SEzyHhm AWmJ5f84QMKcAioSrdsXgF0sKqAscWDbcaYJjIKzkHTPQtI9C6F7ASPzKkbJ1ILi3PTcYsMC o7zUcr3ixNzi0rx0veT83E2M4IjS0trBuGfVB71DjEwcjIcYJTiYlUR4uw+dSxLiTUmsrEot yo8vKs1JLT7EKM3BoiTOe6HrZLyQQHpiSWp2ampBahFMlomDU6qBaVej45fXpSvq3nv08btd un7K8e1FdtnrvCsnLHTmT/03qSctlHGK9SSbbymJ6R/6T7/YdmXl7/+Cvrc0lt/1eB2+285I kyn8h4XZJcvA86yiWyLzGlMsjnJULP3E5p7+z/rWqo+fmi9deXdO/0qujeO6DA/xegZ9DSOd oKhmu7e5zl8+dz5SzPx0VPfafpcp+fNNLc6cVNt4iqfuVIlMYWPGm85DXW8bggSlTOIPOdUm XN57wZRt/d1PR8XqRSr37si8LGV348TlV14ix6xnT192+Ng6k6uL7jUIvtDcfy+gTH2hVeTD 61l3xM0CrQ+EuC3I3GZ8RkzzwG/WMM90J5Uf8tq+O5I5GVryw/NPKLEUZyQaajEXFScCAG5T 2vAXAwAA X-CMS-MailID: 20220714082448epcas5p1a3497e7ce59fe8b5388afe8c3edfc6d0 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----jllqsR28.5W1KdEnZlWKzx60EIuo6gwqBUS1IW9J_3KKio4g=_12d5b0_" CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20220711110824epcas5p22c8e945cb8c3c3ac46c8c2b5ab55db9b References: <20220711110155.649153-1-joshi.k@samsung.com> <20220711110155.649153-4-joshi.k@samsung.com> <2b644543-9a54-c6c4-fd94-f2a64d0701fa@kernel.dk> <43955a42-7185-2afc-9a55-80cc2de53bf9@grimberg.me> <96fcba9a-76ad-8e04-e94e-b6ec5934f84e@grimberg.me> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org ------jllqsR28.5W1KdEnZlWKzx60EIuo6gwqBUS1IW9J_3KKio4g=_12d5b0_ Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Disposition: inline On Thu, Jul 14, 2022 at 11:40:46AM +0800, Ming Lei wrote: >On Mon, Jul 11, 2022 at 09:22:54PM +0300, Sagi Grimberg wrote: >> >> > > > Use the leftover space to carve 'next' field that enables linking of >> > > > io_uring_cmd structs. Also introduce a list head and few helpers. >> > > > >> > > > This is in preparation to support nvme-mulitpath, allowing multiple >> > > > uring passthrough commands to be queued. >> > > >> > > It's not clear to me why we need linking at that level? >> > >> > I think the attempt is to allow something like blk_steal_bios that >> > nvme leverages for io_uring_cmd(s). >> >> I'll rephrase because now that I read it, I think my phrasing is >> confusing. >> >> I think the attempt is to allow something like blk_steal_bios that >> nvme leverages, but for io_uring_cmd(s). Essentially allow io_uring_cmd >> to be linked in a requeue_list. > >io_uring_cmd is 1:1 with pt request, so I am wondering why not retry on >io_uring_cmd instance directly via io_uring_cmd_execute_in_task(). > >I feels it isn't necessary to link io_uring_cmd into list. If path is not available, retry is not done immediately rather we wait for path to be available (as underlying controller may still be resetting/connecting). List helped as command gets added into it (and submitter/io_uring gets the control back), and retry is done exact point in time. But yes, it won't harm if we do couple of retries even if path is known not to be available (somewhat like iopoll). As this situation is not common. And with that scheme, we don't have to link io_uring_cmd. Sagi: does this sound fine to you? ------jllqsR28.5W1KdEnZlWKzx60EIuo6gwqBUS1IW9J_3KKio4g=_12d5b0_ Content-Type: text/plain; charset="utf-8" ------jllqsR28.5W1KdEnZlWKzx60EIuo6gwqBUS1IW9J_3KKio4g=_12d5b0_--