netdev - Re: rib_trie / Fix inflate_threshold

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Date:	Fri, 26 Jun 2009 22:19:32 +0200
From:	Jarek Poplawski <jarkao2@...il.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	Robert Olsson <robert@...ur.slu.se>,
	Robert Olsson <Robert.Olsson@...a.slu.se>,
	Eric Dumazet <dada1@...mosbay.com>,
	=?ISO-8859-2?Q?Pawe=B3_Staszewski?= 
	<pstaszewski@...are.pl>, Robert Olsson <robert.olsson@....uu.se>,
	Linux Network Development list <netdev@...r.kernel.org>
Subject: Re: rib_trie / Fix inflate_threshold_root. Now=15 size=11 bits

On Fri, Jun 26, 2009 at 11:21:43AM -0700, Paul E. McKenney wrote:
> On Fri, Jun 26, 2009 at 08:05:45PM +0200, Jarek Poplawski wrote:
> > On Fri, Jun 26, 2009 at 10:05:38AM -0700, Paul E. McKenney wrote:
> > ...
> > > In that case, simply invoking synchronize_rcu() every once and awhile
> > > should take care of things.  This could be at the end of every large
> > > trie operation, or you could even count the call_rcu() invocations and
> > > do a synchronize_rcu() every 100th, 1,000th, or whatever, based on
> > > the amount of memory available.
> > 
> > OK, for now the minimal change for testing (2.6.30 needs previously
> > mentioned two commits from 2.6.31-rc). (I guess I'll send it with a
> > changelog after net-next is opened.)
> 
> Looks promising to me!!!
> 

Alas, after rethinking, there is one detail which bothers me. Those
largest allocs here are done with vmalloc and freed with RCU by
schedule_work(). So, I wonder if just because of this, the previous
version doing it directly isn't more reliable anyway. Of course, it's
my bad I didn't point it while describing the problem earlier. (I knew
I missed something...;-)

Thanks,
Jarek P.
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