From: Brian King <brking@linux.vnet.ibm.com>
To: Tyrel Datwyler <tyreld@linux.ibm.com>,
james.bottomley@hansenpartnership.com
Cc: martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
brking@linux.ibm.com
Subject: Re: [PATCH v2 01/17] ibmvfc: add vhost fields and defaults for MQ enablement
Date: Fri, 4 Dec 2020 08:26:06 -0600 [thread overview]
Message-ID: <efbfe9e9-c692-80a1-f5b4-55473d8193e4@linux.vnet.ibm.com> (raw)
In-Reply-To: <38903a4f-9253-0b4b-6f67-af78ec86175f@linux.ibm.com>
On 12/2/20 11:27 AM, Tyrel Datwyler wrote:
> On 12/2/20 7:14 AM, Brian King wrote:
>> On 12/1/20 6:53 PM, Tyrel Datwyler wrote:
>>> Introduce several new vhost fields for managing MQ state of the adapter
>>> as well as initial defaults for MQ enablement.
>>>
>>> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
>>> ---
>>> drivers/scsi/ibmvscsi/ibmvfc.c | 9 ++++++++-
>>> drivers/scsi/ibmvscsi/ibmvfc.h | 13 +++++++++++--
>>> 2 files changed, 19 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
>>> index 42e4d35e0d35..f1d677a7423d 100644
>>> --- a/drivers/scsi/ibmvscsi/ibmvfc.c
>>> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c
>>> @@ -5161,12 +5161,13 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>>> }
>>>
>>> shost->transportt = ibmvfc_transport_template;
>>> - shost->can_queue = max_requests;
>>> + shost->can_queue = (max_requests / IBMVFC_SCSI_HW_QUEUES);
>>
>> This doesn't look right. can_queue is the SCSI host queue depth, not the MQ queue depth.
>
> Our max_requests is the total number commands allowed across all queues. From
> what I understand is can_queue is the total number of commands in flight allowed
> for each hw queue.
>
> /*
> * In scsi-mq mode, the number of hardware queues supported by the LLD.
> *
> * Note: it is assumed that each hardware queue has a queue depth of
> * can_queue. In other words, the total queue depth per host
> * is nr_hw_queues * can_queue. However, for when host_tagset is set,
> * the total queue depth is can_queue.
> */
>
> We currently don't use the host wide shared tagset.
Ok. I missed that bit... In that case, since we allocate by default only 100
event structs. If we slice that across IBMVFC_SCSI_HW_QUEUES (16) queues, then
we end up with only about 6 commands that can be outstanding per queue,
which is going to really hurt performance... I'd suggest bumping up
IBMVFC_MAX_REQUESTS_DEFAULT from 100 to 1000 as a starting point.
Thanks,
Brian
--
Brian King
Power Linux I/O
IBM Linux Technology Center
next prev parent reply other threads:[~2020-12-04 14:28 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 0:53 [PATCH v2 00/17] ibmvfc: initial MQ development Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 01/17] ibmvfc: add vhost fields and defaults for MQ enablement Tyrel Datwyler
2020-12-02 15:14 ` Brian King
2020-12-02 17:27 ` Tyrel Datwyler
2020-12-04 14:26 ` Brian King [this message]
2020-12-07 11:56 ` Hannes Reinecke
2020-12-08 22:37 ` Tyrel Datwyler
2020-12-17 11:49 ` John Garry
2020-12-02 0:53 ` [PATCH v2 02/17] ibmvfc: define hcall wrapper for registering a Sub-CRQ Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 03/17] ibmvfc: add Subordinate CRQ definitions Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 04/17] ibmvfc: add alloc/dealloc routines for SCSI Sub-CRQ Channels Tyrel Datwyler
2020-12-02 15:25 ` Brian King
2020-12-02 22:23 ` Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 05/17] ibmvfc: add Sub-CRQ IRQ enable/disable routine Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 06/17] ibmvfc: add handlers to drain and complete Sub-CRQ responses Tyrel Datwyler
2020-12-02 15:46 ` Brian King
2020-12-02 22:28 ` Tyrel Datwyler
2020-12-02 15:56 ` Brian King
2020-12-02 0:53 ` [PATCH v2 07/17] ibmvfc: define Sub-CRQ interrupt handler routine Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 08/17] ibmvfc: map/request irq and register Sub-CRQ interrupt handler Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 09/17] ibmvfc: implement channel enquiry and setup commands Tyrel Datwyler
2020-12-02 15:51 ` Brian King
2020-12-02 0:53 ` [PATCH v2 10/17] ibmvfc: advertise client support for using hardware channels Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 11/17] ibmvfc: set and track hw queue in ibmvfc_event struct Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 12/17] ibmvfc: send commands down HW Sub-CRQ when channelized Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 13/17] ibmvfc: register Sub-CRQ handles with VIOS during channel setup Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 14/17] ibmvfc: add cancel mad initialization helper Tyrel Datwyler
2020-12-02 16:00 ` Brian King
2020-12-02 0:53 ` [PATCH v2 15/17] ibmvfc: send Cancel MAD down each hw scsi channel Tyrel Datwyler
2020-12-02 18:27 ` Brian King
2020-12-02 22:09 ` Tyrel Datwyler
2020-12-02 0:53 ` [PATCH v2 16/17] ibmvfc: enable MQ and set reasonable defaults Tyrel Datwyler
2020-12-02 18:31 ` Brian King
2020-12-02 0:53 ` [PATCH v2 17/17] ibmvfc: provide modules parameters for MQ settings Tyrel Datwyler
2020-12-02 18:40 ` Brian King
2020-12-02 22:17 ` Tyrel Datwyler
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