From: Dave Chinner <david@fromorbit.com>
To: Kanchan Joshi <joshi.k@samsung.com>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org,
linux-ext4@vger.kernel.org, axboe@fb.com, prakash.v@samsung.com,
anshul@samsung.com, joshiiitr@gmail.com
Subject: Re: [PATCH v3 3/7] block: add write-hint to stream-id conversion
Date: Mon, 1 Apr 2019 16:08:21 +1100 [thread overview]
Message-ID: <20190401050821.GQ23020@dastard> (raw)
In-Reply-To: <1553846032-4451-4-git-send-email-joshi.k@samsung.com>
On Fri, Mar 29, 2019 at 01:23:48PM +0530, Kanchan Joshi wrote:
> Earlier this conversion was done by driver (nvme). Current conversion
> is of the form "streamid = write-hint - 1", for both user and kernel
> streams (note that existing infra takes care that user-streams do not
> bump into kernel ones).
Unless we add new user streams, then all the kernel streams change
ID. I'll deal with this in more detail in a later patch.
> Conversion takes stream limit (maintained in
> request queue) into account. Write-hints beyond the queue-limit turn
> to 0.
> New field 'streamid' has been added in request. While 'write-hint' field
> continues to exist. It keeps original value passed from upper layer, and
> used during merging checks.
>
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> ---
> block/blk-core.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3c5f61c..c86daed 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -727,6 +727,25 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
> return false;
> }
>
> +enum rw_hint blk_write_hint_to_streamid(struct request *req,
> + struct bio *bio)
> +{
> + enum rw_hint streamid, nr_streams;
> + struct request_queue *q = req->q;
> + nr_streams = q->limits.nr_streams;
> +
> + streamid = bio->bi_write_hint;
> + if (!nr_streams || streamid == WRITE_LIFE_NOT_SET ||
> + streamid == WRITE_LIFE_NONE)
> + streamid = 0;
> + else {
> + --streamid;
What's this magic thing do?
> + if(streamid > nr_streams)
> + streamid = 0;
So, basically, we'll compress all the kernel hints down to "no hint"
if there are more user streams than the device supports?
Surely we should be reserving a stream for the kernel hints separate
from the user and "none" streams when we have limited device streams
available...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2019-04-01 5:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20190329075737epcas1p4f32cad26279c1146982a6c91b3378eab@epcas1p4.samsung.com>
2019-03-29 7:53 ` [PATCH v3 0/7] Extend write-hint for in-kernel use Kanchan Joshi
[not found] ` <CGME20190329075743epcas1p12f1d290e65ddf84eb74ed94a5ae6eb74@epcas1p1.samsung.com>
2019-03-29 7:53 ` [PATCH v3 1/7] block: extend stream count " Kanchan Joshi
2019-03-30 17:48 ` Andreas Dilger
2019-04-01 5:02 ` Dave Chinner
[not found] ` <CGME20190329075746epcas1p19e5a93c1f593b5fed3f98eddf9159aa5@epcas1p1.samsung.com>
2019-03-29 7:53 ` [PATCH v3 2/7] block: introduce API to register stream information with block layer Kanchan Joshi
[not found] ` <CGME20190329075749epcas2p22b85cbdbb7ccb4f7f3ecf69b84f75dc9@epcas2p2.samsung.com>
2019-03-29 7:53 ` [PATCH v3 3/7] block: add write-hint to stream-id conversion Kanchan Joshi
2019-04-01 5:08 ` Dave Chinner [this message]
2019-04-02 9:20 ` Jan Kara
2019-04-02 20:35 ` Dave Chinner
2019-04-03 9:36 ` Jan Kara
2019-04-03 14:47 ` kanchan
[not found] ` <CGME20190329075753epcas1p16ce37362f83ccb8520a782b845dcb905@epcas1p1.samsung.com>
2019-03-29 7:53 ` [PATCH v3 4/7] nvme: register stream info with block layer Kanchan Joshi
2019-03-29 16:58 ` Heitke, Kenneth
[not found] ` <CGME20190329075755epcas2p2d2670db217ae3519d2c4b93d5e3749d1@epcas2p2.samsung.com>
2019-03-29 7:53 ` [PATCH v3 5/7] fs: introduce APIs to enable sending write-hint with buffer-head Kanchan Joshi
[not found] ` <CGME20190329075758epcas1p335511dcb10bb5592ea72409a1d01e752@epcas1p3.samsung.com>
2019-03-29 7:53 ` [PATCH v3 6/7] fs: introduce write-hint start point for in-kernel hints Kanchan Joshi
2019-04-01 5:12 ` Dave Chinner
2019-04-03 14:30 ` kanchan
[not found] ` <CGME20190329075800epcas2p4731f10eabf7d70dc7096117d161b05a3@epcas2p4.samsung.com>
2019-03-29 7:53 ` [PATCH v3 7/7] fs/ext4,jbd2: add support for passing write-hint with journal Kanchan Joshi
2019-03-30 17:49 ` Andreas Dilger
2019-04-02 9:07 ` Jan Kara
2019-04-03 2:57 ` Martin K. Petersen
2019-04-03 13:42 ` kanchan
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