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Re: [PATCH] local_t : Documentation
- From: Pavel Machek <pavel at ucw dot cz>
- To: Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>
- Cc: linux-kernel at vger dot kernel dot org, Andrew Morton <akpm at osdl dot org>, Ingo Molnar <mingo at redhat dot com>, Greg Kroah-Hartman <gregkh at suse dot de>, Christoph Hellwig <hch at infradead dot org>, ltt-dev at shafik dot org, systemtap at sources dot redhat dot com, Douglas Niehaus <niehaus at eecs dot ku dot edu>, "Martin J. Bligh" <mbligh at mbligh dot org>, Thomas Gleixner <tglx at linutronix dot de>
- Date: Tue, 9 Jan 2007 23:41:00 +0100
- Subject: Re: [PATCH] local_t : Documentation
- References: <20061221001545.GP28643@Krystal> <20061223093358.GF3960@ucw.cz> <20070109031446.GA29426@Krystal>
Hi!
> > > These patches extend and standardise local_t operations on each architectures,
> > > allowing a rich set of atomic operations to be done on per-cpu data with
> > > minimal performance impact. On some architectures, there seems to be no
> > > difference between the SMP and UP operation (same memory barriers, same
> > > LOCking), local.h simply includes asm-generic/local.h, which removes duplicated
> > > code.
> >
> > Could you provide some Documentation/? Knowing when local_t can be
> > used is kind-of important.
>
> Hi Pavel,
>
> Thanks for this appropriate comment. I totally agree that there is a need for
> documentation about how local_t variables should be used. Here is the patch
> that adds Documentation/local_ops.txt. Comments are welcome.
AFAICT this fails to mention... Is local_t as big as int? As big as
long? Or perhaps smaller because high bits may be needed for locking?
Pavel
--
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