Re: Exposing linux libpcap ring buffer usage information

[Guy Harris <guy () alum mit edu>]

On Jul 15, 2009, at 12:45 PM, Dustin Spicuzza wrote:

> I've attached a git patch to add a function, pcap_buffer_stats() to  
> the
> pcap API. I noticed some other platforms use the handle- 
> >opt.buffer_size
> variable, but I don't have access to build any of those so I didn't  
> try
> an implementation of this API for them.

...and those particular statistics might not apply to them; I haven't  
looked at your patch in detail, but, for example, the FreeBSD memory- 
mapped capture mechanism appears (from what I've seen in passing) to  
preserve the BPF store buffer/hold buffer model, where packets are  
appended to the store buffer and a "read" involves re-designating the  
store buffer as the hold buffer, marking the hold buffer as empty, and  
re-designating it as the store buffer, a read() copies the hold buffer  
to userland, and in memory-mapped mode the user-mode code extracts  
packets from the hold buffer.

I'll have to look at the patch a little more and think about it; it  
might be that we'd just make the stats API platform-dependent.
-
This is the tcpdump-workers list.
Visit https://cod.sandelman.ca/ to unsubscribe.