CONFIG_TULIP_NAPI_HW_MITIGATION latency question.

CONFIG_TULIP_NAPI_HW_MITIGATION latency question.

[Justin Piszcz]

"at the cost of a small latency"

How much additional latency is added with this option enabled?

5ms? 10ms?

-> Use Interrupt Mitigation
   x CONFIG_TULIP_NAPI_HW_MITIGATION:
   x Use HW to reduce RX interrupts. Not strict necessary since NAPI 
reduces RX interrupts but itself. Although this reduces RX interrupts even at 
low levels traffic at the cost of a small latency. 
x
   x If in doubt, say Y. 
x

CONFIG_TULIP_NAPI_HW_MITIGATION latency question.

[Robert Olsson]

Justin Piszcz writes:
 > "at the cost of a small latency"
 > 
 > How much additional latency is added with this option enabled?
 > 
 > 5ms? 10ms?
 > 
 > -> Use Interrupt Mitigation
 >    x CONFIG_TULIP_NAPI_HW_MITIGATION:
 >    x Use HW to reduce RX interrupts. Not strict necessary since NAPI 
 > reduces RX interrupts but itself. Although this reduces RX interrupts even at 
 > low levels traffic at the cost of a small latency. 
 > x
 >    x If in doubt, say Y. 

 Hello!

 It's in usec and the tulip only enables this latency when it's needed it
 really tries to keep latency down. 

 It has three steeps of input control.

 Low rate:     No driver latency. No interrupt delay at all.
 Medium rate:  Samll driver latency.
 High rate:    Polling via ->poll

						--ro

Re: CONFIG_TULIP_NAPI_HW_MITIGATION latency question.

[Justin Piszcz]

Thanks for the info.

On Thu, 25 Nov 2004, Robert Olsson wrote:

>
>
>
> Justin Piszcz writes:
> > "at the cost of a small latency"
> >
> > How much additional latency is added with this option enabled?
> >
> > 5ms? 10ms?
> >
> > -> Use Interrupt Mitigation
> >    x CONFIG_TULIP_NAPI_HW_MITIGATION:
> >    x Use HW to reduce RX interrupts. Not strict necessary since NAPI
> > reduces RX interrupts but itself. Although this reduces RX interrupts even at
> > low levels traffic at the cost of a small latency.
> > x
> >    x If in doubt, say Y.
>
> Hello!
>
> It's in usec and the tulip only enables this latency when it's needed it
> really tries to keep latency down.
>
> It has three steeps of input control.
>
> Low rate:     No driver latency. No interrupt delay at all.
> Medium rate:  Samll driver latency.
> High rate:    Polling via ->poll
>
> 						--ro
>