[PATCH rfc 3/6] nvme-pci: Use irq-poll for completion processing

Sagi Grimberg sagi at grimberg.me
Wed Oct 5 09:57:11 PDT 2016

>> @@ -49,6 +50,7 @@
>>  #define NVME_AQ_DEPTH		256
>>  #define SQ_SIZE(depth)		(depth * sizeof(struct nvme_command))
>>  #define CQ_SIZE(depth)		(depth * sizeof(struct nvme_completion))
>> +#define NVME_POLL_BUDGET_IRQ	256
> Is there a reason for the 256 or is it just a nicely suited value?

Umm, No good reason behind it, I used this value before for irq-poll
and it seemed to fit best. We can try other budgets or have it
configurable. The point is to not abuse the soft-irq context for too
long and maintain fairness between completion queues so we just need
a reasonable value.

> Especially
> as you've been using INT_MAX as a budget for CQ processing before (which I
> think is kinda high).

That was just for keeping the existing logic before we change to

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