Subject: Re: [RFC] Use RCU for tcp_ehash lookup

From: "David S. Miller" <[email-masked]>
Date: Wed, 1 Sep 2004 22:43:06 -0700

On Tue, 31 Aug 2004 15:54:20 +0200
Andi Kleen <[email-masked]> wrote:

> And it should also fix the performance problems with
> cat /proc/net/tcp on ppc64/ia64 for large hash tables because the rw locks 
> are gone.

Time to convert netstat et al. over the netlink too.

> > - I presume that one of the reasons for keeping the hash table so big is to
> >   keep lock contention low (& to reduce the size of hash chains). If the lookup
> >   is made lock-free, then could the size of the hash table be reduced (without
> >   adversely impacting performance)?
> 
> Definitely worth trying IMHO. The current hash tables are far
> too big. I would do that as followon patches though.

The hashes are big to make the hash effective, not to help the locking
contention.