"Michael S. Tsirkin" <[EMAIL PROTECTED]> wrote on 04/25/2006 07:58:39 AM:
> Quoting r. Shirley Ma <[EMAIL PROTECTED]>:
> > different drivers have different implementations for CQ completion handler.
>
> Maybe these drivers should be changed then? Its a bit hard for me
> to imagine a
> driver that doesn't get hardware interrupts in IRQ context. So why can't
> completion handler be called directly from there as well?
>
> --
> MST
These completion handler are called directly from these, but under different contexts.
The drivers does get hardware interrupts in IRQ context, but you can always split
the handler into two parts, hardware interrupt context and software interrupt context.
The more light weigh in hardware interrupts, the better.
IPoIB completion polling would be very heavy if the HCA is faster enough.
And the driver implementation shouldn't prevent IPoIB to use both send/recv CQ
handlers from working simultanously. We do see the dramatic performance improvement
on ehca with splitting CQs. With current mthca implementation, polling CQs in hardware
context, it does prevent to use two CQ handlers simultanously since there is only one
hardware interrupt for both send and recv.
I am working on a patch to see whether using work queue in IPoIB completion polling
with splitting CQs would improve performance for all drivers.
Thanks
Shirley Ma
IBM Linux Technology Center
15300 SW Koll Parkway
Beaverton, OR 97006-6063
Phone(Fax): (503) 578-7638
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