Re: Kernel deadlock using nbd over acenic driver.

[Jes Sorensen <jes@wildopensource.com>]

>>>>> "Xiangping" == chen, xiangping <chen_xiangping@emc.com> writes:

Xiangping> But the acenic driver author suggested that sndbuf should
Xiangping> be at least 262144, and the sndbuf can not exceed
Xiangping> r/wmem_default. Is that correct?

Ehm, the acenic author is me ;-)

The default value is what all sockets are assigned on open, you can
adjust this using SO_SNDBUF and SO_RCVBUF, however the values you set
cannot exceed the [rw]mem_max values. Basically if you set the default
to 4MB, your telnet sockets will have a 4MB default limit as well
which may not be what you want (not saying it will use 4MB).

Thus, set the _max values and use SO_SNDBUF and SO_RCVBUF to set the
per process values. But leave the _default values to their original
setting.

Xiangping> So for gigabit Ethernet driver, what is the optimal mem
Xiangping> configuration for performance and reliability?

It depends on your application, number of streams, general usage of
the connection etc. There's no perfect-for-all magic number.

Jes