On Thu, Oct 02, 2003 at 01:32:27PM -0500, Steve Modica wrote:
> We've been doing some experiments here with large numbers of adapters on a
> 64p Linux system.
> When running 8 threads and 8 cpus, the do_gettimeofday code starts to use a
> lot of time.
That's a known problem. The funny thing is that the only users
of this time stamp is SO_TIMESTAMP, which is rarely used (except tcpdump)
and something in DECnet. IMHO the right fix is to add a global
counter that counts all all sockets that use SO_TIMESTAMP and when it's
zero never call it. Decnet could be probably fixed to just use jiffies
like TCP does.
Drawback is that when you enable SO_TIMESTAMP there is a small time window
when the packets are not time stamped yet. The socket layer can just fill
in the current time though.