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Subject: Re: [PATCH RFC v2 12/24] hpsa: use reserved commands
To:     John Garry <john.garry@huawei.com>, Ming Lei <ming.lei@redhat.com>
Cc:     axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com,
        bvanassche@acm.org, hch@infradead.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>
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From:   Hannes Reinecke <hare@suse.de>
Message-ID: <881b6a9b-2137-946f-a900-5c4e6cf1fe37@suse.de>
Date:   Tue, 17 Mar 2020 10:48:44 +0100
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On 3/17/20 10:38 AM, John Garry wrote:
> On 11/03/2020 08:10, Ming Lei wrote:
>>> ands(struct ctlr_info *h)
>>> @@ -5803,6 +5803,7 @@ static int hpsa_scsi_host_alloc(struct 
>>> ctlr_info *h)
>>>       sh->max_lun = HPSA_MAX_LUN;
>>>       sh->max_id = HPSA_MAX_LUN;
>>>       sh->can_queue = h->nr_cmds - HPSA_NRESERVED_CMDS;
>>> +    sh->nr_reserved_cmds = HPSA_NRESERVED_CMDS;
>> Now .nr_reserved_cmds has been passed to blk-mq, you need to increase
>> sh->can_queue to h->nr_cmds, because .can_queue is the whole queue depth
>> (include the part of reserved tags), otherwise, IO tags will be
>> decreased.
>>
> 
> Sounds correct.
> 
I will have having a look at the patchset; I thought I did a patch to 
modify .can_queue so that it would cover only the usable tags, not the 
reserved ones.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                               +49 911 74053 688
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