On 5/31/19 10:21 AM, Ming Lei wrote:
> On Fri, May 31, 2019 at 09:41:58AM +0200, Hannes Reinecke wrote:
>> (Resending due to missing mailing list submission)
>>
>> Update v3 to support SCSI multiqueue.
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
>> ---
>> drivers/scsi/hisi_sas/hisi_sas.h | 1 -
>> drivers/scsi/hisi_sas/hisi_sas_main.c | 45 +++++++++++++++++-----------------
>> drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 44 +++++++++++----------------------
>> 3 files changed, 36 insertions(+), 54 deletions(-)
>>
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
>> index fc87994b5d73..4b6f32f60689 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas.h
>> +++ b/drivers/scsi/hisi_sas/hisi_sas.h
>> @@ -378,7 +378,6 @@ struct hisi_hba {
>> u32 intr_coal_count; /* Interrupt count to coalesce */
>>
>> int cq_nvecs;
>> - unsigned int *reply_map;
>>
>> /* debugfs memories */
>> u32 *debugfs_global_reg;
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
>> index 8a7feb8ed8d6..f4237c4754a4 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas_main.c
>> +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
>> @@ -200,16 +200,12 @@ static void hisi_sas_slot_index_set(struct hisi_hba *hisi_hba, int slot_idx)
>> set_bit(slot_idx, bitmap);
>> }
>>
>> -static int hisi_sas_slot_index_alloc(struct hisi_hba *hisi_hba,
>> - struct scsi_cmnd *scsi_cmnd)
>> +static int hisi_sas_slot_index_alloc(struct hisi_hba *hisi_hba)
>> {
>> int index;
>> void *bitmap = hisi_hba->slot_index_tags;
>> unsigned long flags;
>>
>> - if (scsi_cmnd)
>> - return scsi_cmnd->request->tag;
>> -
>> spin_lock_irqsave(&hisi_hba->lock, flags);
>> index = find_next_zero_bit(bitmap, hisi_hba->slot_index_count,
>> hisi_hba->last_slot_index + 1);
>
> Then you switch to hisi_sas_slot_index_alloc() for allocating the unique
> tag via spin_lock & find_next_zero_bit(). Do you think this way is more
> efficient than blk-mq's sbitmap?
>
slot_index_alloc() is only used for commands which do _not_ have a tag
(eg internal commands), or for v2 hardware which has weird allocation rules.
> The worsen thing is that V3's actual max queue depth is (4096 - 96), but
> this patch claims that the device can support (4096 - 96) * 32 command
> slots, finally hisi_sas_slot_index_alloc() is used to respect the actual
> max queue depth(4000).
>
Well, this patch is an RFC to demonstrate my idea. Of course the queue
depth should be identical before and after the conversion.
> Big contention is caused on hisi_sas_slot_index_alloc(), meantime huge> memory is wasted for request pool.
>
See above. That allocation is only used if no blk tag is available.
Or, at least, that was the idea :-)
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
