On Mon, 2010-01-25 at 11:50 -0600, Joel Schopp wrote:
> > Look at the cputhreads.h implementation ... Today we only support
> > power-of-two numbers of threads.
> >
> I've run 3 threads using cpu hotplug to offline 1 of the 4. It's
> certainly a stupid idea, but there you go.
Oh, you mean yo
Benjamin Herrenschmidt wrote:
On Wed, 2010-01-20 at 16:09 -0600, Joel Schopp wrote:
I can turn that into a conditional branch (case statement) with a shift
for the common 1,2,4 cases which should cover all procs available today
falling back to a divide for any theoretical future processors t
On Wed, 2010-01-20 at 16:09 -0600, Joel Schopp wrote:
> I can turn that into a conditional branch (case statement) with a shift
> for the common 1,2,4 cases which should cover all procs available today
> falling back to a divide for any theoretical future processors that do
> other numbers of th
On Wed, 2010-01-20 at 16:44 -0600, Joel Schopp wrote:
>
> Care to take Gautham's bugfix patch (patch 1/2) now, since it just fixes
> a bug? You'll need it if you ever try to make the x86 broken version work.
Sure, I'll take that, thanks!
___
Linuxppc
Peter Zijlstra wrote:
On Wed, 2010-01-20 at 14:04 -0600, Joel Schopp wrote:
On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
there is performance benefit to idling the higher numbered threads in
the core.
So this is an actual performance improvement, not only po
+
+static inline int thread_in_smt4core(int x)
+{
+ return x % 4;
+}
Needs a whitespace here though I don't really like the above. Any reason
why you can't use the existing cpu_thread_in_core() ?
I will change it to cpu_thread_in_core()
+unsigned long arch_scale_smt_power(struct
+ if (cpu_has_feature(CPU_FTRS_POWER7) && weight == 4) {
I think we should avoid using cpu_has_feature like this. It's better to
create a new feature and add it to POWER7 in the cputable, then check
for that here.
The way that it is now, I think any CPU that has superset of the PO
> > On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
> > there is performance benefit to idling the higher numbered threads in
> > the core.
>
> So this is an actual performance improvement, not only power savings?
It's primarily a performance improvement. Any power/ener
On Wed, 2010-01-20 at 14:04 -0600, Joel Schopp wrote:
> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
> there is performance benefit to idling the higher numbered threads in
> the core.
>
> This patch implements arch_scale_smt_power to dynamically update smt
> thread po
> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
> there is performance benefit to idling the higher numbered threads in
> the core.
>
> This patch implements arch_scale_smt_power to dynamically update smt
> thread power in these idle cases in order to prefer threads 0,1
On Wed, 2010-01-20 at 14:04 -0600, Joel Schopp wrote:
> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
> there is performance benefit to idling the higher numbered threads in
> the core.
So this is an actual performance improvement, not only power savings?
> This patch
On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
there is performance benefit to idling the higher numbered threads in
the core.
This patch implements arch_scale_smt_power to dynamically update smt
thread power in these idle cases in order to prefer threads 0,1 over
thread
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