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Re: [PATCH] Tweak tracing allocation sizes

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH] Tweak tracing allocation sizes
From: Andi Kleen <andi@xxxxxxxxxxxxxx>
Date: Wed, 3 Sep 2008 09:06:54 +0200
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>, lachlan@xxxxxxx, xfs-dev <xfs-dev@xxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
In-reply-to: <20080902215516.GE9204@xxxxxxxxxxxxx>
References: <48BCD3BE.5040107@xxxxxxx> <20080902055604.GD15962@disturbed> <48BCD93E.9040407@xxxxxxx> <87fxojvy5v.fsf@xxxxxxxxxxxxxxxxx> <20080902215516.GE9204@xxxxxxxxxxxxx>
User-agent: Mutt/1.4.2.1i
On Tue, Sep 02, 2008 at 05:55:16PM -0400, Christoph Hellwig wrote:
> On Tue, Sep 02, 2008 at 08:50:52AM +0200, Andi Kleen wrote:
> > > alternative - maybe a very large global trace buffer that is allocated at 
> > > mount
> > > time and shared by all inodes?
> > 
> > You could use vmalloc(). While that is also not fast it will at least
> > not stall.
> 
> In fact kmem_alloc first tries vmalloc, and then falls back to slab
> when it fails.  See fs/xfs/linux-2.6/kmem.c:kmem_alloc().

You mean the other way around? 

Anyways it sounds like like MAX_SLAB_SIZE is just too big.

-Andi

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