Regarding connector netlink running out of buffer space.

[Jeff Haran]

> -----Original Message-----
> From: kernelnewbies-bounces at kernelnewbies.org [mailto:kernelnewbies-
> bounces at kernelnewbies.org] On Behalf Of mindentropy
> Sent: Friday, July 29, 2011 1:35 PM
> To: kernelnewbies at kernelnewbies.org
> Subject: Regarding connector netlink running out of buffer space.
> 
> Hi,
>   I am trying to benchmark connector netlink and am passing a file and
> sending
> the same to listening userspace app's using connectors i.e. cat
filename >
> /dev/myconnector and an app listening. When I do this I always run
into
> ENOBUFS or "No buffer space available" for files greater than 2MB.
> Now how should I fix this?
> a) Increase the socket buffers? My rmem_max is 131071 and rmem_default
> is
> 126976
> b) Should I check for the seq and ack and resend the packets? If yes
how
> much
> packets should I not discard to do a resend?
> 
> Are there any other ways? Also I am not sure why local loop would
cause
> enobufs? I am running this on a quad core with 3G of RAM.
> 
> Thanks.

Just guessing here, but it's possible the kernel is attempting to
kmalloc() a single buffer for the whole file and with the file at 2MB
there's no slab/slob/slub with buffers that big. You might need to write
to /dev/myconnector in smaller chunks.

Again, just a guess.