Messages in this thread | | | Subject | Re: [PATCH 02/11] hisi_sas: alloc queue id of slot according to device id | From | John Garry <> | Date | Wed, 16 Nov 2016 10:02:47 +0000 |
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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 > > . >
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