Date: Wed, 24 Nov 2010 09:54:01 -0500
From: Jason Baron <jbaron@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: rostedt@goodmis.org, mingo@elte.hu, mathieu.desnoyers@polymtl.ca,
        hpa@zytor.com, tglx@linutronix.de, andi@firstfloor.org,
        roland@redhat.com, rth@redhat.com, masami.hiramatsu.pt@hitachi.com,
        fweisbec@gmail.com, avi@redhat.com, davem@davemloft.net,
        sam@ravnborg.org, ddaney@caviumnetworks.com, michael@ellerman.id.au,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] jump label: add enabled/disabled state to jump
	label key entries
Message-ID: <20101124145401.GA2815@redhat.com>
References: <cover.1290546539.git.jbaron@redhat.com> <d03959060763fecdf2523a3f1353e1fc59f8f4a1.1290546539.git.jbaron@redhat.com> <1290586809.2072.424.camel@laptop>
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On Wed, Nov 24, 2010 at 09:20:09AM +0100, Peter Zijlstra wrote:
> On Tue, 2010-11-23 at 16:27 -0500, Jason Baron wrote:
> >         struct hlist_head modules;
> >         unsigned long key;
> > +       u32 nr_entries : 31,
> > +              enabled :  1;
> >  }; 
> 
> I still don't see why you do this, why not simply mandate that the key
> is of type atomic_t* and use *key as enabled state?
> 

Because I want to use *key as a pointer directly to 'struct jump_label_entry'.
In this way jump_label_enable(), jump_label_disable(), become O(1) operations.
That way we don't need any hashing.

thanks,

-Jason
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