Re: Shrink the held_lock struct by using bitfields.

From: Dave Jones
Date: Tue Jan 02 2007 - 20:06:56 EST


On Wed, Jan 03, 2007 at 01:47:36AM +0100, Bodo Eggert wrote:
> Dave Jones <davej@xxxxxxxxxx> wrote:
>
> > Shrink the held_lock struct by using bitfields.
> > This shrinks task_struct on lockdep enabled kernels by 480 bytes.
>
> > * The following field is used to detect when we cross into an
> > * interrupt context:
> > */
> > - int irq_context;
> [...]
> > + unsigned char irq_context:1;
> [...]
>
> Can these fields be set by concurrent processes, e.g.:
> CPU0 CPU1
> load flags
> load flags
> flip bit
> store
> flip bit
> store

It's a per-process structure.

Dave

--
http://www.codemonkey.org.uk
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