[ntp:questions] NTP vs RADclock?

Rick Jones rick.jones2 at hp.com
Mon Jun 11 17:16:59 UTC 2012


unruh <unruh at invalid.ca> wrote:
> On 2012-06-10, Rick Jones <rick.jones2 at hp.com> wrote:
> > I'd like to see the full output of ethtool, ethtool -i and ethtool
> > -c for your interfaces if I may.  Feel free to send as direct
> > email if you prefer.

> info:10.0[unruh]>ethtool -i eth0                   
> driver: e1000                                      
> version: 7.3.21-k8-NAPI                            
> firmware-version: N/A                              
> bus-info: 0000:06:00.0                             
> info:10.0[unruh]>ethtool -c eth0                   
> Coalesce parameters for eth0:                      
> Adaptive RX: off  TX: off                          
> stats-block-usecs: 0
> sample-interval: 0
> pkt-rate-low: 0
> pkt-rate-high: 0

> rx-usecs: 3
> rx-frames: 0
> rx-usecs-irq: 0
> rx-frames-irq: 0


Might go ahead and set rx-usecs to zero.  The Intel drivers have (or
at least had) a module parameter called InterruptThrottleRate which
tries to be rather clever.

http://www.intel.com/support/network/adapter/pro100/sb/CS-032516.htm

I'm not sure just at the moment how that shows-up in the ethtool
output though.

> The fact that the distribution in round trip times is almost a
> perfect square pulse (Ie, constant probability between the minimum
> 1.4us to the max .4us) suggests that may it is polling rather than
> interrupt, altough the card certainly has an interrupt

At this stage in the Linux kernel I don't believe that NAPI can be
disabled.  I believe it switches over to polling only after some
threshold though.  Pehaps mentioned in the previous URLs.

rick jones
-- 
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway... :)
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