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

Tony Varriale tvarriale at comcast.net
Mon Jan 25 14:53:33 EST 2010


Assuming the config isn't huge and your router is already oversubbed you 
shouldn't be able to tell.

tv
----- Original Message ----- 
From: "Saku Ytti" <saku at ytti.fi>
To: <cisco-nsp at puck.nether.net>
Sent: Monday, January 25, 2010 10:06 AM
Subject: Re: [c-nsp] Wr mem causes massive delay...


> 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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