[ntp:questions] NTP vs RADclock?

Rick Jones rick.jones2 at hp.com
Mon Jun 11 23:41:28 UTC 2012


unruh <unruh at invalid.ca> wrote:
> Tried that. Makes no difference to scatter of return time on the
> client. Do not know if that means that interrupt coalescence is
> still on, or that it makes not difference. The problem appears to be
> in the receipt of the packets, not the transmission (although I
> guess it could still coalesce interrupts on receipt as well. )

Avoiding TX completion interrupts started happening with 100BT NICs.
Schemes like only taking a TX compltion interrupt when it covered more
than half the transmit queue, and then checking TX completions on RX
interrupts.  Coalescing RX completion interrupts arrived with GbE
NICs.  If you have all the values as zeros, then presumably there
should be a 1-1 between interrupts and packets sent/received.
Presumably then there should be a 1-1 between packets sent/received
(ifconfig or ethtool -S) and counters incrementing in /proc/interrupts
for the IRQ(s) of the interface.

rick jones
-- 
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