From: John Garry <john.garry@huawei.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: <axboe@kernel.dk>, <jejb@linux.ibm.com>,
<martin.petersen@oracle.com>, <linux-block@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-scsi@vger.kernel.org>,
<kashyap.desai@broadcom.com>, <hare@suse.de>
Subject: Re: [PATCH v2 08/11] blk-mq: Add blk_mq_ops.init_request_no_hctx()
Date: Wed, 18 Aug 2021 09:46:30 +0100 [thread overview]
Message-ID: <9a723528-3d4f-4b80-b10a-12ef50b00c50@huawei.com> (raw)
In-Reply-To: <YRy5C1s0HetZCHQ1@T590>
On 18/08/2021 08:38, Ming Lei wrote:
> On Mon, Aug 09, 2021 at 10:29:35PM +0800, John Garry wrote:
>> Add a variant of the init_request function which does not pass a hctx_idx
>> arg.
>>
>> This is important for shared sbitmap support, as it needs to be ensured for
>> introducing shared static rqs that the LLDD cannot think that requests
>> are associated with a specific HW queue.
>>
>> Signed-off-by: John Garry<john.garry@huawei.com>
>> ---
>> block/blk-mq.c | 15 ++++++++++-----
>> include/linux/blk-mq.h | 7 +++++++
>> 2 files changed, 17 insertions(+), 5 deletions(-)
>>
>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>> index f14cc2705f9b..4d6723cfa582 100644
>> --- a/block/blk-mq.c
>> +++ b/block/blk-mq.c
>> @@ -2427,13 +2427,15 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
>> static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
>> unsigned int hctx_idx, int node)
>> {
>> - int ret;
>> + int ret = 0;
>>
>> - if (set->ops->init_request) {
>> + if (set->ops->init_request)
>> ret = set->ops->init_request(set, rq, hctx_idx, node);
>> - if (ret)
>> - return ret;
>> - }
>> + else if (set->ops->init_request_no_hctx)
>> + ret = set->ops->init_request_no_hctx(set, rq, node);
Hi Ming,
> The only shared sbitmap user of SCSI does not use passed hctx_idx, not
> sure we need such new callback.
Sure, actually most versions of init_request callback don't use
hctx_idx. Or numa_node arg.
> If you really want to do this, just wondering why not pass '-1' as
> hctx_idx in case of shared sbitmap?
Yeah, I did consider that. hctx_idx is an unsigned, and I generally
don't like -1U - but that's no big deal. But I also didn't like how it
relies on the driver init_request callback to check the value, which
changes the semantics.
Obviously we don't add new versions of init_request for new block
drivers which use shared sbitmap everyday, and any new ones would get it
right.
I suppose I can go the way you suggest - I just thought that this method
was neat as well.
Thanks,
John
next prev parent reply other threads:[~2021-08-18 8:46 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-09 14:29 [PATCH v2 00/11] blk-mq: Reduce static requests memory footprint for shared sbitmap John Garry
2021-08-09 14:29 ` [PATCH v2 01/11] blk-mq: Change rqs check in blk_mq_free_rqs() John Garry
2021-08-09 14:29 ` [PATCH v2 02/11] block: Rename BLKDEV_MAX_RQ -> BLKDEV_DEFAULT_RQ John Garry
2021-08-09 14:29 ` [PATCH v2 03/11] blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests() John Garry
2021-08-18 3:49 ` Ming Lei
2021-08-09 14:29 ` [PATCH v2 04/11] blk-mq: Invert check " John Garry
2021-08-18 3:53 ` Ming Lei
2021-08-09 14:29 ` [PATCH v2 05/11] blk-mq-sched: Rename blk_mq_sched_alloc_{tags -> map_and_request}() John Garry
2021-08-18 3:55 ` Ming Lei
2021-08-09 14:29 ` [PATCH v2 06/11] blk-mq: Pass driver tags to blk_mq_clear_rq_mapping() John Garry
2021-08-09 17:00 ` kernel test robot
2021-08-09 17:10 ` John Garry
2021-08-09 19:55 ` kernel test robot
2021-08-18 4:02 ` Ming Lei
2021-08-18 12:00 ` John Garry
2021-08-19 0:39 ` Ming Lei
2021-08-19 7:32 ` John Garry
2021-08-23 2:59 ` Ming Lei
2021-08-09 14:29 ` [PATCH v2 07/11] blk-mq: Add blk_mq_tag_update_sched_shared_sbitmap() John Garry
2021-08-18 7:28 ` Ming Lei
2021-08-09 14:29 ` [PATCH v2 08/11] blk-mq: Add blk_mq_ops.init_request_no_hctx() John Garry
2021-08-18 7:38 ` Ming Lei
2021-08-18 8:46 ` John Garry [this message]
2021-08-09 14:29 ` [PATCH v2 09/11] scsi: Set blk_mq_ops.init_request_no_hctx John Garry
2021-08-09 14:29 ` [PATCH v2 10/11] blk-mq: Use shared tags for shared sbitmap support John Garry
2021-08-18 8:16 ` Ming Lei
2021-08-18 14:18 ` John Garry
2021-08-23 8:55 ` John Garry
2021-08-09 14:29 ` [PATCH v2 11/11] blk-mq: Stop using pointers for blk_mq_tags bitmap tags John Garry
2021-08-18 8:18 ` Ming Lei
2021-08-17 7:02 ` [PATCH v2 00/11] blk-mq: Reduce static requests memory footprint for shared sbitmap John Garry
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