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To: "David S. Miller" <davem@redhat.com>
cc: linux-kernel@vger.kernel.org
Subject: Re: stat very inefficient
References: <2mN94-3MP-9@gated-at.bofh.it>
From: Andi Kleen <ak@muc.de>
Date: Wed, 28 Jul 2004 12:16:40 +0200
In-Reply-To: <2mN94-3MP-9@gated-at.bofh.it> (David S. Miller's message of
 "Wed, 28 Jul 2004 05:20:06 +0200")
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"David S. Miller" <davem@redhat.com> writes:

> 1) From inode to "struct kstat"
> 2) From "struct kstat" to "struct stat{,64}" on local kernel stack
> 3) From local kernel stack to userspace

[...]

> I was about to make sparc64 specific copies of all the stat
> system calls in order to optimize this properly.  But that
> makes little sense, instead I think fs/stat.c should call
> upon arch-specific stat{,64} structure fillin routines that
> can do the magic, given a kstat struct.

I think wrappers are preferable to callbacks.  Basically step (2) 
should be eliminated. 

Most architectures can use a generic wrapper for that, together
with a standard macro that clears all the padding in user space.

-Andi