Socket buffer

[Joel Sherrill]

Leon,

This may not help since my head is foggy this morning.  But
The factors that go into the default socket buffering are
tunable in RTEMS.  Look in rtems_bsdnet.h and the documentation.

When you do this though, you have to tell the stack
to reserve enough memory for the mbufs.  You probably
haven't increased the reserved buffers.

--joel

Leon Pollak wrote:
> Hello, all.
>
> I searched WEB and Wiki - was not able to find an answer...:-(
> --
> I see the message "not delivered. Socket buffer full" in 
> rtems_bsdnet_show_udp_stats report.
>
> Ok, I now tried to increase the socket buffer (from 1MB to 2MB) by the command 
> setsockopt(so,SOL_SOCKET,SO_RCVBUF,&Size,sizeof(Size)).
>
>  - failed. 
>
> Debugging shows that function sbreserve fails in the first check:
> /*
>  * Allot mbufs to a sockbuf.
>  * Attempt to scale mbmax so that mbcnt doesn't become limiting
>  * if buffering efficiency is near the normal case.
>  */
> int
> sbreserve(sb, cc)
> 	struct sockbuf *sb;
> 	u_long cc;
> {
>
> 	if (cc > sb_max * MCLBYTES / (MSIZE + MCLBYTES))
> 		return (0);
> ......
>
> Now, when I set sb_max to be 1MB, the max socket buffer size may be also not 
> more then 1MB.
> And I cannot set it higher to 2MB, as the calculation of sb_max * MCLBYTES 
> (which is 2048) exits the 32bit limit.
>
> This makes me think that increasing the socket buffer to such extend is 
> incorrect. If so, what can I do to avoid this error?
>
> I thought that the cause may be in the lack of CPU time, but 
> rtems_cpu_usage_report shows that about 35% CPU spends in IDLE task...
>
> Thanks a lot for any hint.
>