From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ecfrec.frec.bull.fr (ecfrec.frec.bull.fr [129.183.4.8]) by ozlabs.org (Postfix) with ESMTP id E958FDDF46 for ; Thu, 4 Sep 2008 17:24:37 +1000 (EST) Date: Thu, 4 Sep 2008 09:22:52 +0200 From: Sebastien Dugue To: benh@kernel.crashing.org Subject: Re: [PATCH 2/2] powerpc - Make the irq reverse mapping radix tree lockless Message-ID: <20080904092252.12b3df4a@bull.net> In-Reply-To: <1220496739.4879.20.camel@pasglop> References: <1218029429-21114-1-git-send-email-sebastien.dugue@bull.net> <1218029429-21114-3-git-send-email-sebastien.dugue@bull.net> <1219209781.21386.25.camel@pasglop> <20080903154105.7dff49db@bull.net> <1220496739.4879.20.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: dwalker@mvista.com, tinytim@us.ibm.com, linux-rt-users@vger.kernel.org, jean-pierre.dion@bull.net, rostedt@goodmis.org, linux-kernel@vger.kernel.org, michael@ellerman.id.au, linuxppc-dev@ozlabs.org, paulus@samba.org, gilles.carry@ext.bull.net, tglx@linutronix.de List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 04 Sep 2008 12:52:19 +1000 Benjamin Herrenschmidt wrote: > On Wed, 2008-09-03 at 15:41 +0200, Sebastien Dugue wrote: > > On Wed, 20 Aug 2008 15:23:01 +1000 Benjamin Herrenschmidt wrote: > > > > > BTW. It would be good to try to turn the GFP_ATOMIC into GFP_KERNEL, > > > > That would be nice indeed > > > > > maybe using a semaphore instead of a lock to protect insertion vs. > > > initialisation. > > > > a semaphore? are you meaning a mutex? If not, I fail to understand what you're > > implying. > > Right, a mutex, bad habit calling those semaphores from the old days :-) OK, then we're on the same line ;-) > > > Right, that's the problem with this new scheme and I'm still trying > > to find a way to handle memory allocation failures be it for GFP_ATOMIC or > > GFP_KERNEL. > > > > I could not think of anything simple so far and I'm open for suggestions. > > GFP_KERNEL should not fail, it will just block no ? No it won't block and will fail (returns NULL). > If it fails, it's > probably catastrophic enough not to care. Yep, I'd tend to agree with that. > You can always fallback to linear lookup. I will have to add that back as there is no more fallback. > I don't know if it's worth trying to fire off a new > allocation attempt later, probably not. I've been pondering with this lately, but I think that adding a linear lookup fallback should be OK. Thanks, Sebastien. > > Ben. > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-dev >