From: Christoph Hellwig <hch@lst.de>
To: Damien Le Moal <dlemoal@kernel.org>
Cc: Bart Van Assche <bvanassche@acm.org>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
"Martin K . Petersen" <martin.petersen@oracle.com>,
Christoph Hellwig <hch@lst.de>,
Niklas Cassel <Niklas.Cassel@wdc.com>,
Avri Altman <Avri.Altman@wdc.com>, Bean Huo <huobean@gmail.com>,
Daejun Park <daejun7.park@samsung.com>,
Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH v2 03/15] block: Support data lifetime in the I/O priority bitfield
Date: Mon, 16 Oct 2023 08:17:37 +0200 [thread overview]
Message-ID: <20231016061737.GA26670@lst.de> (raw)
In-Reply-To: <8aec03bb-4cef-9423-0ce4-c10d060afce4@kernel.org>
On Fri, Oct 06, 2023 at 05:19:52PM +0900, Damien Le Moal wrote:
> Your change seem to assume that it makes sense to be able to combine CDL with
> lifetime hints. But does it really ?
Yes, it does.
> CDL is of dubious value for solid state
> media and as far as I know,
No, it's pretty useful and I'd bet my 2 cents that it will eventually
show up in relevant standards and devices.
Even if it wasn't making our user interfaces exclusive would be a
massive pain.
> The other question here if you really want to keep the bit separation approach
> is: do we really need up to 64 different lifetime hints ? While the scsi
> standard allows that much, does this many different lifetime make sense in
> practice ? Can we ever think of a usecase that needs more than say 8 different
> liftimes (3 bits) ? If you limit the number of possible lifetime hints to 8,
> then we can keep 4 bits unused in the hint field for future features.
Yes, I think this is the smoking gun. We should be fine with a much
more limited number of lifetime hints, i.e. the user interface only
exposes 5 hints, and supporting more in the in-kernel interfaces seems
of rather doubtfuŀ use.
next prev parent reply other threads:[~2023-10-16 6:17 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 19:40 [PATCH v2 00/15] Pass data temperature information to UFS devices Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 01/15] block: Make bio_set_ioprio() modify fewer bio->bi_ioprio bits Bart Van Assche
2023-10-06 6:28 ` Kanchan Joshi
2023-10-06 18:20 ` Bart Van Assche
2023-10-10 5:22 ` Kanchan Joshi
2023-10-11 16:52 ` Bart Van Assche
2023-10-12 8:49 ` Kanchan Joshi
2023-10-12 14:03 ` Niklas Cassel
2023-10-12 17:42 ` Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 02/15] blk-ioprio: Modify " Bart Van Assche
2023-10-06 6:36 ` Kanchan Joshi
2023-10-06 18:25 ` Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 03/15] block: Support data lifetime in the I/O priority bitfield Bart Van Assche
2023-10-06 6:42 ` Kanchan Joshi
2023-10-06 8:19 ` Damien Le Moal
2023-10-06 9:53 ` Niklas Cassel
2023-10-06 18:07 ` Bart Van Assche
2023-10-11 20:51 ` Bart Van Assche
2023-10-12 1:02 ` Damien Le Moal
2023-10-12 18:00 ` Bart Van Assche
2023-10-13 1:08 ` Damien Le Moal
2023-10-13 9:33 ` Niklas Cassel
2023-10-13 21:20 ` Bart Van Assche
2023-10-16 9:20 ` Niklas Cassel
2023-10-16 16:36 ` Bart Van Assche
2023-10-13 20:18 ` Bart Van Assche
2023-10-15 22:22 ` Damien Le Moal
2023-10-16 16:31 ` Bart Van Assche
2023-10-16 6:17 ` Christoph Hellwig [this message]
2023-10-16 16:32 ` Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 04/15] fs: Restore write hint support Bart Van Assche
2023-10-10 5:42 ` Kanchan Joshi
2023-10-11 16:56 ` Bart Van Assche
2023-10-16 6:20 ` Christoph Hellwig
2023-10-05 19:40 ` [PATCH v2 05/15] fs/f2fs: Restore the whint_mode mount option Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 06/15] scsi: core: Query the Block Limits Extension VPD page Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 07/15] scsi_proto: Add structures and constants related to I/O groups and streams Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 08/15] sd: Translate data lifetime information Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 09/15] scsi_debug: Reduce code duplication Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 10/15] scsi_debug: Support the block limits extension VPD page Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 11/15] scsi_debug: Rework page code error handling Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 12/15] scsi_debug: Rework subpage " Bart Van Assche
2023-10-05 19:40 ` [PATCH v2 13/15] scsi_debug: Implement the IO Advice Hints Grouping mode page Bart Van Assche
2023-10-05 19:41 ` [PATCH v2 14/15] scsi_debug: Implement GET STREAM STATUS Bart Van Assche
2023-10-05 19:41 ` [PATCH v2 15/15] scsi_debug: Maintain write statistics per group number Bart Van Assche
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