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Wed, 8 Jul 2020 22:40:03 +0900 (KST) Received: from epsmtrp2.samsung.com (unknown [182.195.40.14]) by epcas5p3.samsung.com (KnoxPortal) with ESMTPA id 20200708130103epcas5p3d4d6a9a340f405e2a955e25018ee3556~fyIRMr2S42478724787epcas5p3s; Wed, 8 Jul 2020 13:01:03 +0000 (GMT) Received: from epsmgms1p2.samsung.com (unknown [182.195.42.42]) by epsmtrp2.samsung.com (KnoxPortal) with ESMTP id 20200708130103epsmtrp270b27ef57ecfe75ed707c6eca2d72753~fyIRLoUAN0037100371epsmtrp25; Wed, 8 Jul 2020 13:01:03 +0000 (GMT) X-AuditID: b6c32a4b-39fff70000002503-5d-5f05ccb34d82 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p2.samsung.com (Symantec Messaging Gateway) with SMTP id 23.6C.08303.F83C50F5; Wed, 8 Jul 2020 22:01:03 +0900 (KST) Received: from test-zns (unknown [107.110.206.5]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20200708130101epsmtip241d423671fe7c7d46015b34ba48814a3~fyIOx-zaa1837818378epsmtip2g; Wed, 8 Jul 2020 13:01:00 +0000 (GMT) Date: Wed, 8 Jul 2020 18:28:05 +0530 From: Kanchan Joshi To: Jens Axboe Cc: Matthew Wilcox , viro@zeniv.linux.org.uk, bcrl@kvack.org, hch@infradead.org, Damien.LeMoal@wdc.com, asml.silence@gmail.com, linux-fsdevel@vger.kernel.org, mb@lightnvm.io, linux-kernel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-block@vger.kernel.org, Selvakumar S , Nitesh Shetty , Javier Gonzalez Subject: Re: [PATCH v3 4/4] io_uring: add support for zone-append Message-ID: <20200708125805.GA16495@test-zns> MIME-Version: 1.0 In-Reply-To: <145cc0ad-af86-2d6a-78b3-9ade007aae52@kernel.dk> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrLKsWRmVeSWpSXmKPExsWy7bCmlu7mM6zxBhuXalvMWbWN0WL13X42 i65/W1gsWtu/MVmcnrCIyeJd6zkWi8d3PrNbTJnWxGix95a2xZ69J1ksLu+aw2axYvsRFott v+czW7z+cZLN4vzf46wWv3/MYXMQ8Ng56y67x+YVWh6Xz5Z6bPo0id2j++oPRo++LasYPT5v kvNoP9DN5LHpyVumAM4oLpuU1JzMstQifbsErozrc26wFswXrZjS9JGlgbFVsIuRk0NCwERi 4Z4XLCC2kMBuRomFOwu7GLmA7E+MEk/adrBBOJ8ZJb5M+MQC07Fo0w1miMQuRom9tyeyQjjP GCV+b2wFq2IRUJHYsHotexcjBwebgKbEhcmlIGERAQWJnt8rwaYyC2xklri59BtYvbCAo8Tn nScZQep5BXQl3p4qAQnzCghKnJz5BKyEU8BW4smrq4wgtqiAssSBbceZIA56wCGxscMApFVC wEWib4IORFhY4tXxLewQtpTE53d72SDsYolfd46C3S8h0MEocb1hJtRj9hIX9/wFm8kskCGx Y+scqGZZiamn1kHF+SR6fz+B2ssrsWMejK0ocW/SU1YIW1zi4YwlULaHxIVbx9kh4fOPWWLl lEusExjlZyH5bRaSfRC2lUTnhybWWUD/MAtISyz/xwFhakqs36W/gJF1FaNkakFxbnpqsWmB cV5quV5xYm5xaV66XnJ+7iZGcArU8t7B+OjBB71DjEwcjIcYJTiYlUR4DRRZ44V4UxIrq1KL 8uOLSnNSiw8xSnOwKInzKv04EyckkJ5YkpqdmlqQWgSTZeLglGpgao8wWM/8uPLt0V47sWMV Qhl/rpz8feV3cdm9ew0cL+JWFCQ+e7ltSXaqT5H3T86LW/e0CBbtzc6ZEp2TuL6xxM9H6LzV jvVsT7K+PFbfzfs77MT/r8emtVdIrVBY/mBX9bUKVtGsyY9sA4N4Pxd8z/s5Mf7Gn++lv/Jv nl5x5+KZ8AdCn1c4Mbgu57zkpM37TtjWKdb29+r0h7FX+rRYvdpi72xYIRLMHyDuEa4u9NHy YsJKa7GpMhfSnvB0vLq7+8rlHB1LqfOJ1iwsE8RU7mqFG6XPK6kIXFAnOSWUV+6Y3xHV4+5r 3+aXZ8UrpHxdYjnD6u1CP5nDIhnzqyeE3y6790zbzKjynWDnlndrlViKMxINtZiLihMB1E5i +PADAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprNIsWRmVeSWpSXmKPExsWy7bCSvG7/YdZ4g/lXlCzmrNrGaLH6bj+b Rde/LSwWre3fmCxOT1jEZPGu9RyLxeM7n9ktpkxrYrTYe0vbYs/ekywWl3fNYbNYsf0Ii8W2 3/OZLV7/OMlmcf7vcVaL3z/msDkIeOycdZfdY/MKLY/LZ0s9Nn2axO7RffUHo0ffllWMHp83 yXm0H+hm8tj05C1TAGcUl01Kak5mWWqRvl0CV0b7xOlMBReFKuZdvszUwHiRr4uRk0NCwERi 0aYbzF2MXBxCAjsYJQ7vbGCCSIhLNF/7wQ5hC0us/PecHaLoCaPE+yd3mUESLAIqEhtWrwVK cHCwCWhKXJhcChIWEVCQ6Pm9kg2knllgK7PE14Oz2UASwgKOEp93nmQEqecV0JV4e6oEYuY/ ZolZf7eALeMVEJQ4OfMJC4jNLGAmMW/zQ2aQemYBaYnl/zhAwpwCthJPXl1lBLFFBZQlDmw7 zjSBUXAWku5ZSLpnIXQvYGRexSiZWlCcm55bbFhglJdarlecmFtcmpeul5yfu4kRHH9aWjsY 96z6oHeIkYmD8RCjBAezkgivgSJrvBBvSmJlVWpRfnxRaU5q8SFGaQ4WJXHer7MWxgkJpCeW pGanphakFsFkmTg4pRqY+KqKZfdM2KjitqXh4Z0D4tEPG5aqnfshnDl540qvozfWWv5eq5d3 wLHAcaJKsJD8xvpcM+eLmdMqJyxZVfztb9+5gOKvxwM2puT0LnDfw3Woc/elReFrftjw2f2Z /9n4dERSdKpOetodd4638hfETqxivC8b2mgVHlLUt0+/4qKA/KMZKs9fn7v0wVf31X6/rwXn KyQ8KoOvqP6zXSJus+dnyh2Tz7ULXGa0N1c+N5nJfnVXy3kxYf3fTrOl/F7xmTAa7XhwJWBd r3/6HfVLyxxF+zMPxpQuP3Rtrf1UI9EXv+clhGt7h/0q3ZLLYq6sYXHW/r+YbbHee17xiwmL 23NERT/cmOl16N6ZjTMYlFiKMxINtZiLihMB9zl9Yy4DAAA= X-CMS-MailID: 20200708130103epcas5p3d4d6a9a340f405e2a955e25018ee3556 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----FBC7EIImzEv-3WQrgwRbJYn4xAlwhlhWWV1zALX9mq8rjZSB=_e89f5_" X-Sendblock-Type: REQ_APPROVE CMS-TYPE: 105P X-CMS-RootMailID: 20200707223803epcas5p41814360c764d6b5f67fdbf173a8ba64e References: <20200706141002.GZ25523@casper.infradead.org> <4a9bf73e-f3ee-4f06-7fad-b8f8861b0bc1@kernel.dk> <20200706143208.GA25523@casper.infradead.org> <20200707151105.GA23395@test-zns> <20200707155237.GM25523@casper.infradead.org> <20200707202342.GA28364@test-zns> <7a44d9c6-bf7d-0666-fc29-32c3cba9d1d8@kernel.dk> <20200707221812.GN25523@casper.infradead.org> <145cc0ad-af86-2d6a-78b3-9ade007aae52@kernel.dk> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org ------FBC7EIImzEv-3WQrgwRbJYn4xAlwhlhWWV1zALX9mq8rjZSB=_e89f5_ Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Disposition: inline On Tue, Jul 07, 2020 at 04:37:55PM -0600, Jens Axboe wrote: >On 7/7/20 4:18 PM, Matthew Wilcox wrote: >> On Tue, Jul 07, 2020 at 02:40:06PM -0600, Jens Axboe wrote: >>>>> so we have another 24 bytes before io_kiocb takes up another cacheline. >>>>> If that's a serious problem, I have an idea about how to shrink struct >>>>> kiocb by 8 bytes so struct io_rw would have space to store another >>>>> pointer. >>>> Yes, io_kiocb has room. Cache-locality wise whether that is fine or >>>> it must be placed within io_rw - I'll come to know once I get to >>>> implement this. Please share the idea you have, it can come handy. >>> >>> Except it doesn't, I'm not interested in adding per-request type fields >>> to the generic part of it. Before we know it, we'll blow past the next >>> cacheline. >>> >>> If we can find space in the kiocb, that'd be much better. Note that once >>> the async buffered bits go in for 5.9, then there's no longer a 4-byte >>> hole in struct kiocb. >> >> Well, poot, I was planning on using that. OK, how about this: > >Figured you might have had your sights set on that one, which is why I >wanted to bring it up upfront :-) > >> +#define IOCB_NO_CMPL (15 << 28) >> >> struct kiocb { >> [...] >> - void (*ki_complete)(struct kiocb *iocb, long ret, long ret2); >> + loff_t __user *ki_uposp; >> - int ki_flags; >> + unsigned int ki_flags; >> >> +typedef void ki_cmpl(struct kiocb *, long ret, long ret2); >> +static ki_cmpl * const ki_cmpls[15]; >> >> +void ki_complete(struct kiocb *iocb, long ret, long ret2) >> +{ >> + unsigned int id = iocb->ki_flags >> 28; >> + >> + if (id < 15) >> + ki_cmpls[id](iocb, ret, ret2); >> +} >> >> +int kiocb_cmpl_register(void (*cb)(struct kiocb *, long, long)) >> +{ >> + for (i = 0; i < 15; i++) { >> + if (ki_cmpls[id]) >> + continue; >> + ki_cmpls[id] = cb; >> + return id; >> + } >> + WARN(); >> + return -1; >> +} > >That could work, we don't really have a lot of different completion >types in the kernel. Thanks, this looks sorted. The last thing is about the flag used to trigger this processing. Will it be fine to intoduce new flag (RWF_APPEND2 or RWF_APPEND_OFFSET) instead of using RWF_APPEND? New flag will do what RWF_APPEND does and will also return the written-location (and therefore expects pointer setup in application). ------FBC7EIImzEv-3WQrgwRbJYn4xAlwhlhWWV1zALX9mq8rjZSB=_e89f5_ Content-Type: text/plain; charset="utf-8" ------FBC7EIImzEv-3WQrgwRbJYn4xAlwhlhWWV1zALX9mq8rjZSB=_e89f5_--