lkml.org 
[lkml]   [2016]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 02/11] hisi_sas: alloc queue id of slot according to device id
From
Date
On 16/11/2016 01:41, Zhangfei Gao wrote:
> On Mon, Nov 7, 2016 at 8:48 PM, John Garry <john.garry@huawei.com> wrote:
>> From: Xiang Chen <chenxiang66@hisilicon.com>
>>
>> Currently slots are allocated from queues in a round-robin fashion.
>> This causes a problem for internal commands in device mode. For this
>> mode, we should ensure that the internal abort command is the last
>> command seen in the host for that device. We can only ensure this when
>> we place the internal abort command after the preceding commands for
>> device that in the same queue, as there is no order in which the host
>> will select a queue to execute the next command.
>
> Is there performance penalty, since only one queue is supported for a device.

Hi Zhangfei,

From testing I have not seen any noteable performance change. However,
please note the comment on mq, below.

Cheers,
John

>
>>
>> This queue restriction makes supporting scsi mq more tricky in
>> the future, but should not be a blocker.
>>
>> Note: Even though v1 hw does not support internal abort, the
>> allocation method is chosen to be the same for consistency.
>>
>> Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
>> Signed-off-by: John Garry <john.garry@huawei.com>
>
> Reviewed-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> .
>


\
 
 \ /
  Last update: 2016-11-16 11:03    [W:0.128 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site