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From: Keith Busch <[email protected]>
To: Kanchan Joshi <[email protected]>
Cc: [email protected], [email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected]
Subject: Re: [RFC PATCH v3 2/3] nvme: keep nvme_command instead of pointer to it
Date: Tue, 16 Mar 2021 10:16:28 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On Tue, Mar 16, 2021 at 07:31:25PM +0530, Kanchan Joshi wrote:
> nvme_req structure originally contained a pointer to nvme_command.
> Change nvme_req structure to keep the command itself.
> This helps in avoiding hot-path memory-allocation for async-passthrough.

I have a slightly different take on how to handle pre-allocated
passthrough commands. Every transport except PCI already preallocates a
'struct nvme_command' within the pdu, so allocating another one looks
redundant. Also, it does consume quite a bit of memory for something
that is used only for the passthrough case.

I think we can solve both concerns by always using the PDU nvme_command
rather than have the transport drivers provide it. I just sent the patch
here if you can take a look. It tested fine on PCI and loop (haven't
tested any other transports).

 http://lists.infradead.org/pipermail/linux-nvme/2021-March/023711.html

  reply	other threads:[~2021-03-16 17:17 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20210316140229epcas5p23d68a4c9694bbf7759b5901115a4309b@epcas5p2.samsung.com>
2021-03-16 14:01 ` [RFC PATCH v3 0/3] Async nvme passthrough over io_uring Kanchan Joshi
     [not found]   ` <CGME20210316140233epcas5p372405e7cb302c61dba5e1094fa796513@epcas5p3.samsung.com>
2021-03-16 14:01     ` [RFC PATCH v3 1/3] io_uring: add helper for uring_cmd completion in submitter-task Kanchan Joshi
2021-03-16 15:43       ` Stefan Metzmacher
2021-03-18  1:57       ` Jens Axboe
2021-03-18  5:25         ` Kanchan Joshi
2021-03-18  5:48           ` Christoph Hellwig
2021-03-18  6:14             ` Kanchan Joshi
     [not found]   ` <CGME20210316140236epcas5p4de087ee51a862402146fbbc621d4d4c6@epcas5p4.samsung.com>
2021-03-16 14:01     ` [RFC PATCH v3 2/3] nvme: keep nvme_command instead of pointer to it Kanchan Joshi
2021-03-16 17:16       ` Keith Busch [this message]
2021-03-17  9:38         ` Kanchan Joshi
2021-03-17 14:17           ` Keith Busch
     [not found]   ` <CGME20210316140240epcas5p3e71bfe2afecd728c5af60056f21cc9b7@epcas5p3.samsung.com>
2021-03-16 14:01     ` [RFC PATCH v3 3/3] nvme: wire up support for async passthrough Kanchan Joshi
2021-03-17  8:52       ` Christoph Hellwig
2021-03-17 16:49         ` Jens Axboe
2021-03-17 16:59           ` Christoph Hellwig
2021-03-17 17:21             ` Jens Axboe
2021-03-17 18:59               ` Jens Axboe
2021-03-18  5:54         ` Kanchan Joshi
2021-03-17 16:45       ` Keith Busch
2021-03-17 17:02         ` Christoph Hellwig
2021-03-16 15:51   ` [RFC PATCH v3 0/3] Async nvme passthrough over io_uring Jens Axboe
2021-03-17  9:31     ` Kanchan Joshi
2021-03-18  1:58       ` Jens Axboe
2021-03-18  7:47         ` Kanchan Joshi

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