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Date: Mon, 12 Nov 2001 17:30:14 -0800
From: Mike Fedyk <mfedyk@matchmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: "David S. Miller" <davem@redhat.com>, helgehaf@idb.hist.no,
        linux-kernel@vger.kernel.org
Subject: Re: speed difference between using hard-linked and modular drives?
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On Tue, Nov 13, 2001 at 10:14:22AM +1100, Rusty Russell wrote:
> In message <20011112.152304.39155908.davem@redhat.com> you write:
> >    From: Rusty Russell <rusty@rustcorp.com.au>
> >    Date: Mon, 12 Nov 2001 20:59:05 +1100
> > 
> >    (atomic_inc & atomic_dec_and_test for every packet, anyone?).
> > 
> > We already do pay that price, in skb_release_data() :-)
> 
> Sorry, I wasn't clear!  skb_release_data() does an atomic ops on the
> skb data region, which is almost certainly on the same CPU.  This is
> an atomic op on a global counter for the module, which almost
> certainly isn't.
> 
> For something which (statistically speaking) never happens (module
> unload).
>

Is this in the fast path or slow path?

If it only happens on (un)load, then there isn't any cost until it's needed...

Mike
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