Re: Kernel deadlock using nbd over acenic driver.

[Jes Sorensen <jes@wildopensource.com>]

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

xiangping> Hi, When the system stucks, I could not get any response
xiangping> from the console or terminal.  But basically the only
xiangping> network connections on both machine are the nbd connection
xiangping> and a couple of telnet sessions. That is what shows on
xiangping> "netstat -t".

xiangping> /proc/sys/net/ipv4/tcp_[rw]mem are "4096 262144 4096000",
xiangping> /proc/sys/net/core/*mem_default are 4096000,
xiangping> /proc/sys/net/core/*mem_max are 8192000, I did not change
xiangping> /proc/sys/net/ipv4/tcp_mem.

Don't do this, setting the [rw]mem_default values to that is just
insane. Do it in the applications that needs it and nowhere else.

xiangping> The system was low in memory, I started up 20 to 40 thread
xiangping> to do block write simultaneously.

If you have a lot of outstanding connections and active threads, it's
not unlikely you run out of memory if each socket eats 4MB.

Jes