From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [PATCH RFC] v1 expedited "big hammer" RCU grace periods Date: Thu, 23 Apr 2009 08:47:02 -0700 (PDT) Message-ID: References: <20090423052520.GA13036@linux.vnet.ibm.com> <20090423075436.GB22606@elte.hu> <20090423153402.GC6877@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Ingo Molnar , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, akpm@linux-foundation.org, davem@davemloft.net, dada1@cosmosbay.com, zbr@ioremap.net, jeff.chua.linux@gmail.com, paulus@samba.org, laijs@cn.fujitsu.com, jengelh@medozas.de, r000n@r000n.net, benh@kernel.crashing.org, mathieu.desnoyers@polymtl.ca To: "Paul E. McKenney" Return-path: In-Reply-To: <20090423153402.GC6877@linux.vnet.ibm.com> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 23 Apr 2009, Paul E. McKenney wrote: > > Hmmm... I need to ask Jeff Chua what HZ he was running with. Because if > there was some read-side critical section soaking up 30 milliseconds, > all that hammering will do is slow things down... The original bug report comes from simply bootup: "I'm loading all the firewall rules during boot-up and this 6 secs slowness is really not very nice to wait for." IOW, the problematic case likely effectively has _nothing_ else going on. Sure, there might be some parallelism (the bootup scripts are getting better for that), but hopefully not 6 seconds worth, and not likely any complex critical sections. Linus