Re: [PATCH] libata: add support for NCQ commands for SG interface

[Vinayak Kale]

Hi Tejun,

On Fri, Oct 23, 2015 at 11:09 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> Hello,
>
> On Fri, Oct 23, 2015 at 10:01:35AM +0530, Vinayak Kale wrote:
>> > It looks like it'd work given that it's forcing qc->tag into
>> > tf->nsect.  What's the use case tho?
>>
>> We need to issue NCQ commands with priority bit from user space application.
>>
>> BTW, Sergei Shtylyov raised concern regarding usefulness of adding
>> ATA_TFLAG_LBA to tf->flags. Can you please comment on that as well?
>> Accordingly I will either keep it or discard it in V2. Thanks.
>
> I like the change but can you please put that in a separate patch?

Ok. I'll put this in a separate patch.

> Also, can you please verify that this works fine with multiple regular
> NCQ commands in flight?

I verified that multiple FPDMA Read/Write commands issued
simultaneously by different processes, work fine.
I hooked up our application's queued Read/Write APIs to fio, ran fio
for 'random rw' over multiple processes. It worked fine.

>
> Thanks.
>
> --
> tejun
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