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SubjectRe: [PATCH RESEND 0/1] AHCI: Optimize interrupt processing
On 07/29/2013 05:46 AM, Tejun Heo wrote:
> Hello,
>
> On Fri, Jul 26, 2013 at 02:14:36PM -0700, Nicholas A. Bellinger wrote:
>> So I don't think (completely) getting rid of ata_port->qcmds[] will be
>> possible, and just converting the ata_scsi_queuecmd() path to use the
>> extra SHT->cmd_size pre-allocation for *ata_queued_cmd might end up
>> being more trouble that it's worth. Still undecided on that part..
>>
>> Tejun, do you have any thoughts + input here..?
>
> libata exception handling which includes probing doesn't go through
> SCSI at all. It all works inside libata proper using ata_queuecmds
> and only the result is exposed to SCSI. Most of those SCSI semantics
> need to be emulated anyway, so this makes things a lot easier than
> going through SCSI for each command. As it currently stands, it'd be
> a lot of effort to try to embed ata_qc's into higher layer construct.
> Given how it's used, I don't think it's a high priority task.
>
> One thing which would probably be worthwhile tho is getting rid of the
> bitmap based qc tag allocator in libata. That one is just borderline
> stupid to keep around on any setup which is supposed to be scalable.

Your border might be wider than mine :-). Yes, the bitmap should
definitely go.

--
Jens Axboe



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