On Fri, 26 Sep 2008, Mike Travis wrote:

quoted text
> Peter Zijlstra wrote:
> > On Fri, 2008-09-26 at 14:05 -0400, Steven Rostedt wrote:
> >> +struct ring_buffer {
> >> +       unsigned long           size;
> >> +       unsigned                pages;
> >> +       unsigned                flags;
> >> +       int                     cpus;
> >> +       atomic_t                record_disabled;
> >> +
> >> +       struct mutex            mutex;
> >> +
> >> +       /* FIXME: this should be online CPUS */
> >> +       struct ring_buffer_per_cpu *buffers[NR_CPUS];
> > 
> > actually nr_possible makes sense, and you might consider always
> > allocating buffers (and keeping them for offlined cpus) to avoid massive
> > allocations/frees cpu-hotplug events.
> > 
> > Mike Travis has been going over the kernel removing constructs like
> > this, and replacing them with dynamically allocated arrays of
> > nr_possible.
> > 
> >> +};
> 
> The other thing to consider is using a percpu variable.

This structure is allocated on request.

-- Steve

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