Re: Libpcap on VMWare

[Dustin Spicuzza <dustin () virtualroadside com>]

Guy Harris wrote:
> On Jan 12, 2010, at 1:42 PM, Dustin Spicuzza wrote:
>
> > I haven't used the mmap'ed ring buffer on VMWare, but we used a 2GB
> > buffer to allow us to read/process 500Mbps off two interfaces with zero
> > packet loss over the period of a few days.
>
> 32-bit or 64-bit kernel, and 32-bit or 64-bit application?  (My guess would be 64-bit, as a 2GB buffer would eat up 
> half the address space, and I have the impression that the Linux kernel keeps userland in the same address space, 
> rather than having separate kernel and user address spaces, so I'm not sure you could have a 2GB buffer with a 32-bit 
> kernel, and possibly not with a 32-bit userland.)

64-bit kernel and application.

> > We also used pcap_dispatch()
> > to process 1024 packets at a time... so that helped a lot also.
>
> When you say "1024 packets at a time", does that mean you pass 1024 as the cnt argument, so that it doesn't process 
> *more* than 1024 packets at a time?  Does that work better than -1 (meaning "loop until you run out of packets")?

Yes, that was what I meant. We never tried -1. We're running single
threaded with a select loop for pcap on two devices and some network
communications, so we figured on the off chance that -1 would never
return (which I'm sure it would), using a number would be easier.

Dustin


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