[c-nsp] Wr mem causes massive delay...

Saku Ytti saku at ytti.fi
Mon Jan 25 11:06:19 EST 2010


On (2010-01-25 09:34 -0600), Tony Varriale wrote:
 
> If you are pinging through the router, no that is not normal.  There
> will always be some delay while it writes to media.  But, it should
> not affect the forwarding path.

It does, but only slightly, 'write' and 'dir' will both do that, as they
interrupt. This is true at least for VXR, I don't see why 2800 would be
different.
To see these, you'd need non-averaging SLA measurments with very frequent
polling interval, but if you can do that, you can see from transit SLA
graphs e.g. when rancid was ran.
When I've been able to see this, I've used some other methods than simple
ping as the effect is extremely short and thus hard to see with ping.  If
OP was pinging once a second, and can reproduce this every time he does
'write', then this is much more likely real issue.

-- 
  ++ytti


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