> I don't dislike very much the lhash sleep even now as the lhash loop may
> be slowww (lots of sprintf) while under multpile syn flooding attack and
> while under heavy network load with a long backlog of sockets waiting to
> be accepted. I like the other processor to not spin when possible while I
> am looking at the netstat information. I don't think the lhash_user check
> will add a significative overhead to the common case (when luser = 0). If
> you think it's adding a a singificative overhread I'll agree to remove it
> of course.
It will spin in any case. The first thing in tcp_lhash_wlock() is write_lock.
At least current implementation is good only to allow to sleep under
lock. If you do not sleep, it gives no advantages at all.
You are right in general. /proc/net/tcp and other /proc/net/* are
toys for children. I would not allow to access them on loaded servers.
I remember as old times each access /proc/net/tcp generated overruns
on all serial lines 8)8) Anyone may curse reading /dev/kmem, but it is really
the only working method appropirate for adult men yet 8)8)
Alexey
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