From: John Garry <john.garry@huawei.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: <axboe@kernel.dk>, <jejb@linux.ibm.com>,
<martin.petersen@oracle.com>, <hare@suse.de>,
<ming.lei@redhat.com>, <bvanassche@acm.org>,
<linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-scsi@vger.kernel.org>,
<virtualization@lists.linux-foundation.org>,
<esc.storagedev@microsemi.com>, <chenxiang66@hisilicon.com>,
Hannes Reinecke <hare@suse.com>
Subject: Re: [PATCH RFC v2 02/24] scsi: allocate separate queue for reserved commands
Date: Tue, 10 Mar 2020 21:08:56 +0000 [thread overview]
Message-ID: <79cf4341-f2a2-dcc9-be0d-2efc6e83028a@huawei.com> (raw)
In-Reply-To: <20200310183243.GA14549@infradead.org>
On 10/03/2020 18:32, Christoph Hellwig wrote:
> On Wed, Mar 11, 2020 at 12:25:28AM +0800, John Garry wrote:
>> From: Hannes Reinecke <hare@suse.com>
>>
>> Allocate a separate 'reserved_cmd_q' for sending reserved commands.
>
> Why? Reserved command specifically are not in any way tied to queues.
> .
>
So the v1 series used a combination of the sdev queue and the per-host
reserved_cmd_q. Back then you questioned using the sdev queue for virtio
scsi, and the unconfirmed conclusion was to use a common per-host q.
This is the best link I can find now:
https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg83177.html
"
>> My implementation actually allows for per-device reserved tags (eg for
>> virtio). But some drivers require to use internal commands prior to any
>> device setup, so they have to use a separate reserved command queue
just to
>> be able to allocate tags.
>
> Why would virtio-scsi need per-device reserved commands? It
currently uses
> a global mempool to allocate the reset commands.
>
Oh, I'm perfectly fine with dropping the per-device reserved commands,
and use the host-wide queue in general.
It turns out most of the drivers use it that way already.
Will be doing so for the next iteration.
"
Cheers
next prev parent reply other threads:[~2020-03-10 21:09 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 16:25 [PATCH RFC v2 00/24] scsi: enable reserved commands for LLDDs John Garry
2020-03-10 16:25 ` [PATCH RFC v2 01/24] scsi: add 'nr_reserved_cmds' field to the SCSI host template John Garry
2020-03-10 23:08 ` Ming Lei
2020-03-11 6:55 ` Hannes Reinecke
2020-03-11 8:00 ` Ming Lei
2020-03-10 16:25 ` [PATCH RFC v2 02/24] scsi: allocate separate queue for reserved commands John Garry
2020-03-10 18:32 ` Christoph Hellwig
2020-03-10 21:08 ` John Garry [this message]
2020-03-11 6:22 ` Christoph Hellwig
2020-03-11 6:58 ` Hannes Reinecke
2020-03-11 7:51 ` John Garry
2020-04-06 9:05 ` Hannes Reinecke
2020-04-07 11:54 ` John Garry
2020-04-07 14:00 ` Hannes Reinecke
2020-04-07 14:35 ` John Garry
2020-04-07 14:45 ` Hannes Reinecke
2020-04-07 15:19 ` John Garry
2020-04-07 16:30 ` Christoph Hellwig
2020-04-23 14:13 ` John Garry
2020-04-23 14:49 ` Hannes Reinecke
2020-04-23 15:33 ` John Garry
2020-03-10 16:25 ` [PATCH RFC v2 03/24] blk-mq: Implement blk_mq_rq_is_reserved() John Garry
2020-03-10 16:25 ` [PATCH RFC v2 04/24] scsi: Add scsi_{get, put}_reserved_cmd() John Garry
2020-03-10 16:25 ` [PATCH RFC v2 05/24] csiostor: use reserved command for LUN reset John Garry
2020-03-10 16:25 ` [PATCH RFC v2 06/24] scsi: add scsi_cmd_from_priv() John Garry
2020-03-10 16:25 ` [PATCH RFC v2 07/24] virtio_scsi: use reserved commands for TMF John Garry
2020-03-10 16:25 ` [PATCH RFC v2 08/24] scsi: add host tagset busy iterator John Garry
2020-03-10 16:25 ` [PATCH RFC v2 09/24] fnic: use reserved commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 10/24] fnic: use scsi_host_tagset_busy_iter() to traverse commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 11/24] hpsa: move hpsa_hba_inquiry after scsi_add_host() John Garry
2020-03-10 16:25 ` [PATCH RFC v2 12/24] hpsa: use reserved commands John Garry
2020-03-11 8:10 ` Ming Lei
2020-03-17 9:38 ` John Garry
2020-03-17 9:48 ` Hannes Reinecke
2020-03-30 13:42 ` John Garry
2020-03-10 16:25 ` [PATCH RFC v2 13/24] hpsa: use blk_mq_tagset_busy_iter() to traverse outstanding commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 14/24] hpsa: drop refcount field from CommandList John Garry
2020-03-10 16:25 ` [PATCH RFC v2 15/24] snic: use reserved commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 16/24] snic: use tagset iter for traversing commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 17/24] aacraid: move scsi_add_host() John Garry
2020-03-10 16:25 ` [PATCH RFC v2 18/24] aacraid: use private commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 19/24] aacraid: replace cmd_list with scsi_host_tagset_busy_iter() John Garry
2020-03-10 16:25 ` [PATCH RFC v2 20/24] aacraid: use scsi_host_tagset_busy_iter() to traverse outstanding commands John Garry
2020-03-10 16:25 ` [PATCH RFC v2 21/24] dpt_i2o: drop cmd_list usage John Garry
2020-03-10 16:25 ` [PATCH RFC v2 22/24] scsi: drop scsi command list John Garry
2020-03-10 18:35 ` Christoph Hellwig
2020-03-10 20:47 ` John Garry
2020-03-10 16:25 ` [PATCH RFC v2 23/24] scsi: libsas: aic94xx: hisi_sas: mvsas: pm8001: Allocate Scsi_cmd for slow task John Garry
2020-03-10 16:25 ` [PATCH RFC v2 24/24] scsi: hisi_sas: Use libsas slow task SCSI command John Garry
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