Date: Wed, 21 Dec 2005 09:16:47 +0200 (EET)
From: Pekka J Enberg <penberg@cs.Helsinki.FI>
To: Ingo Molnar <mingo@elte.hu>
cc: Steven Rostedt <rostedt@goodmis.org>,
       Christoph Lameter <christoph@lameter.com>,
       Alok N Kataria <alokk@calsoftinc.com>,
       Shobhit Dayal <shobhit@calsoftinc.com>,
       Shai Fultheim <shai@scalex86.org>, Matt Mackall <mpm@selenic.com>,
       Andrew Morton <akpm@osdl.org>, john stultz <johnstul@us.ibm.com>,
       Gunter Ohrner <G.Ohrner@post.rwth-aachen.de>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH RT 00/02] SLOB optimizations
In-Reply-To: <20051221065619.GC766@elte.hu>
Message-ID: <Pine.LNX.4.58.0512210909040.23799@sbz-30.cs.Helsinki.FI>
References: <1134860251.13138.193.camel@localhost.localdomain>
 <20051220133230.GC24408@elte.hu> <Pine.LNX.4.58.0512200836120.21313@gandalf.stny.rr.com>
 <20051220135725.GA29392@elte.hu> <Pine.LNX.4.58.0512200900490.21767@gandalf.stny.rr.com>
 <1135093460.13138.302.camel@localhost.localdomain> <20051220181921.GF3356@waste.org>
 <1135106124.13138.339.camel@localhost.localdomain>
 <84144f020512201215j5767aab2nc0a4115c4501e066@mail.gmail.com>
 <1135114971.13138.396.camel@localhost.localdomain> <20051221065619.GC766@elte.hu>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1516
Lines: 33

Hi Ingo,

Steven Rostedt <rostedt@goodmis.org> wrote:
> > [...] Today's slab system is starting to become like the IDE where 
> > nobody, but a select few sado-masochis, dare to venture in. (I've CC'd 
> > them ;) [...]

On Wed, 21 Dec 2005, Ingo Molnar wrote:
> while it could possibly be cleaned up a bit, it's one of the 
> best-optimized subsystems Linux has. Most of the "unnecessary 
> complexity" in SLAB is related to a performance or a debugging feature.  
> Many times i have looked at the SLAB code in a disassembler, right next 
> to profile output from some hot workload, and have concluded: 'I couldnt 
> do this any better even with hand-coded assembly'.
> 
> SLAB-bashing has become somewhat fashionable, but i really challenge 
> everyone to improve the SLAB code first (to make it more modular, easier 
> to read, etc.), before suggesting replacements.

I dropped working on the replacement because I wanted to do just that. I 
sent my patch only because Matt and Steve talked about writing a 
replacement and thought they would be interested to see it.

I am all for gradual improvements but after taking a stab at it, I 
starting to think rewriting would be easier, simply because the slab 
allocator has been clean-up resistant for so long.

			Pekka
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/