lkml.org 
[lkml]   [2022]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 4/6] scsi: pm8001: Use sas_task_find_rq() for tagging
From
On 30/09/2022 10:17, Jinpu Wang wrote:
> On Fri, Sep 30, 2022 at 11:03 AM John Garry<john.garry@huawei.com> wrote:
>> The request associated with a scsi command coming from the block layer
>> has a unique tag, so use that when possible for getting a CCB.
>>
>> Unfortunately we don't support reserved commands in the SCSI midlayer yet,
>> so in the interim continue to manage those tags internally (along with
>> tags for private commands).
>>
>> Signed-off-by: John Garry<john.garry@huawei.com>
> Reviewed-by: Jack Wang<jinpu.wang@ionos.com>
> nice, I would expect this can improve performance, do you have numbers?

Unfortunately my system hangs after I run for an appreciable period of
time. I normally get around it by turning on much heavy debug options,
but that would not be much use for performance testing.

But we did get considerable performance improvement for hisi_sas when we
made the equivalent change.

Damien, if you are interested then sharing any results would be great.

BTW, I do notice that we still have this global lock in delivery path
which should be removed at some stage:

int mvs_queue_command(struct sas_task *task, gfp_t gfp_flags)
{
...

spin_lock_irqsave(&mvi->lock, flags);
rc = mvs_task_prep(task, mvi, is_tmf, tmf, &pass);
...
spin_unlock_irqrestore(&mvi->lock, flags);
}

That really will affect performance...

Thanks,
John

\
 
 \ /
  Last update: 2022-09-30 12:33    [W:0.062 / U:0.224 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site