Re: Patch: optimizations and improvements for Endace DAG cards.

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

On Nov 19, 2003, at 5:40 PM, Koryn Grant wrote:

> Yes - the (non)blocking support consists of simply setting the 
> appropriate
> flag to call dag_offset() in a (non)blocking way.

So does "dag_open()" return a UNIX-style file descriptor and, if so, 
does setting non-blocking mode on the FD returned by "dag_open()" have 
any effect?

I've just checked in changes to do the setting and getting of 
non-blocking mode in functions pointed to by pointers in the "pcap_t" 
structure, rather than using the pile of #ifdefs and run-time checks we 
had before; if "dag_open()" doesn't return a UNIX-style file 
descriptor, or if it does but setting non-blocking mode on it has no 
effect (or isn't necessary to get "dag_offset()" not to block, you 
could add a "dag_getnonblock()" routine that just checks 
"p->md.dag_offset_flags" and returns 1 if DAGF_NONBLOCK is set and 0 
otherwise, and change "dag_setnonblock()" not to bother calling 
"pcap_setnonblock()".

Also, if "dag_open()" returns a UNIX-style file descriptor (e.g., a 
descriptor referring to the DAG device), can you do a "select()" or 
"poll()" on it, and have it mark that FD as readable iff there are 
packets that have arrived but not yet been read (i.e., if 
dag_mem_bottom hasn't caught up to dag_mem_top, right?)?  If not, that 
might be useful for applications that would want to use "select()" or 
"poll()" to wait for packets to arrive.

-
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