linux-kernel - Re: [PATCH] module: kzalloc mod->ref

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Message-ID: <20090114155859.GO25103@bombadil.infradead.org>
Date:	Wed, 14 Jan 2009 10:58:59 -0500
From:	Kyle McMartin <kyle@...radead.org>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Kyle McMartin <kyle@...radead.org>, rusty@...tcorp.com.au,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: kzalloc mod->ref

On Wed, Jan 14, 2009 at 10:09:59AM +0100, Takashi Iwai wrote:
> At Tue, 13 Jan 2009 22:35:33 -0500,
> Kyle McMartin wrote:
> > 
> > From: Kyle McMartin <kyle@...hat.com>
> > 
> > Dynamically allocate mod->ref instead of fixing it in the struct module.
> > Reduces on disk space wasted in the module .ko, and kills a loop
> > initializing the local_t it contains since we can just kzalloc it.
> > 
> > This matters when we're talking about large NR_CPUS.
> > 
> > Signed-off-by: Kyle McMartin <kyle@...hat.com>
> > ---
> > The patch removing cacheline_aligned from struct module_ref should be
> > applied as well to cut down on the amount of memory we allocate. This
> > patch makes a nice stopgap until we have per_cpu module references.
> > 
> > cheers, Kyle
> 
> Similar patches (including mine) have been already posted, but no
> proceed until now...
> 	http://lkml.org/lkml/2008/11/11/315

Ah, sigh.

It would be nice to get this sorted out, since we're serious wasting
disk space for no good reason...

Although as Richard points out, dropping the cacheline_aligned might
drop networking performance (which, sigh, is also stupid) but allocating
128b * NR_CPUS is just a ridiculous amount of memory to waste for a
reference count...

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