* [PATCH 39/49] arch/s390: replace cpumask_weight with cpumask_weight_eq where appropriate
[not found] <20220210224933.379149-1-yury.norov@gmail.com>
@ 2022-02-10 22:49 ` Yury Norov
2022-02-11 6:54 ` Sven Schnelle
0 siblings, 1 reply; 3+ messages in thread
From: Yury Norov @ 2022-02-10 22:49 UTC (permalink / raw)
To: Yury Norov, Andy Shevchenko, Rasmus Villemoes, Andrew Morton,
Michał Mirosław, Greg Kroah-Hartman, Peter Zijlstra,
David Laight, Joe Perches, Dennis Zhou, Emil Renner Berthing,
Nicholas Piggin, Matti Vaittinen, Alexey Klimov, linux-kernel,
Heiko Carstens, Vasily Gorbik, Christian Borntraeger,
Alexander Gordeev, Sven Schnelle, Thomas Richter,
Sumanth Korikkar, Sebastian Andrzej Siewior, Jiapeng Chong,
kernel test robot, linux-s390
cfset_all_start() calls cpumask_weight() to compare the weight of cpumask
with a given number. We can do it more efficiently with
cpumask_weight_{eq, ...} because conditional cpumask_weight may stop
traversing the cpumask earlier, as soon as condition is (or can't be) met.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
arch/s390/kernel/perf_cpum_cf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index ee8707abdb6a..4d217f7f5ccf 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -975,7 +975,7 @@ static int cfset_all_start(struct cfset_request *req)
return -ENOMEM;
cpumask_and(mask, &req->mask, cpu_online_mask);
on_each_cpu_mask(mask, cfset_ioctl_on, &p, 1);
- if (atomic_read(&p.cpus_ack) != cpumask_weight(mask)) {
+ if (!cpumask_weight_eq(mask, atomic_read(&p.cpus_ack))) {
on_each_cpu_mask(mask, cfset_ioctl_off, &p, 1);
rc = -EIO;
debug_sprintf_event(cf_dbg, 4, "%s CPUs missing", __func__);
--
2.32.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 39/49] arch/s390: replace cpumask_weight with cpumask_weight_eq where appropriate
2022-02-10 22:49 ` [PATCH 39/49] arch/s390: replace cpumask_weight with cpumask_weight_eq where appropriate Yury Norov
@ 2022-02-11 6:54 ` Sven Schnelle
2022-02-11 23:40 ` Yury Norov
0 siblings, 1 reply; 3+ messages in thread
From: Sven Schnelle @ 2022-02-11 6:54 UTC (permalink / raw)
To: Yury Norov
Cc: Andy Shevchenko, Rasmus Villemoes, Andrew Morton,
Michał Mirosław, Greg Kroah-Hartman, Peter Zijlstra,
David Laight, Joe Perches, Dennis Zhou, Emil Renner Berthing,
Nicholas Piggin, Matti Vaittinen, Alexey Klimov, linux-kernel,
Heiko Carstens, Vasily Gorbik, Christian Borntraeger,
Alexander Gordeev, Thomas Richter, Sumanth Korikkar,
Sebastian Andrzej Siewior, Jiapeng Chong, kernel test robot,
linux-s390
Hi Yury,
Yury Norov <yury.norov@gmail.com> writes:
> cfset_all_start() calls cpumask_weight() to compare the weight of cpumask
> with a given number. We can do it more efficiently with
> cpumask_weight_{eq, ...} because conditional cpumask_weight may stop
> traversing the cpumask earlier, as soon as condition is (or can't be) met.
>
> Signed-off-by: Yury Norov <yury.norov@gmail.com>
> ---
> arch/s390/kernel/perf_cpum_cf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
> index ee8707abdb6a..4d217f7f5ccf 100644
> --- a/arch/s390/kernel/perf_cpum_cf.c
> +++ b/arch/s390/kernel/perf_cpum_cf.c
> @@ -975,7 +975,7 @@ static int cfset_all_start(struct cfset_request *req)
> return -ENOMEM;
> cpumask_and(mask, &req->mask, cpu_online_mask);
> on_each_cpu_mask(mask, cfset_ioctl_on, &p, 1);
> - if (atomic_read(&p.cpus_ack) != cpumask_weight(mask)) {
> + if (!cpumask_weight_eq(mask, atomic_read(&p.cpus_ack))) {
> on_each_cpu_mask(mask, cfset_ioctl_off, &p, 1);
> rc = -EIO;
> debug_sprintf_event(cf_dbg, 4, "%s CPUs missing", __func__);
given that you're adding a bunch of these functions - gt,lt,eq and
others, i wonder whether it makes sense to also add cpumask_weight_ne(),
so one could just write:
if (cpumask_weight_ne(mask, atomic_read(&p.cpus_ack))) {
...
}
?
/Sven
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 39/49] arch/s390: replace cpumask_weight with cpumask_weight_eq where appropriate
2022-02-11 6:54 ` Sven Schnelle
@ 2022-02-11 23:40 ` Yury Norov
0 siblings, 0 replies; 3+ messages in thread
From: Yury Norov @ 2022-02-11 23:40 UTC (permalink / raw)
To: Sven Schnelle
Cc: Andy Shevchenko, Rasmus Villemoes, Andrew Morton,
Michał Mirosław, Greg Kroah-Hartman, Peter Zijlstra,
David Laight, Joe Perches, Dennis Zhou, Emil Renner Berthing,
Nicholas Piggin, Matti Vaittinen, Alexey Klimov, linux-kernel,
Heiko Carstens, Vasily Gorbik, Christian Borntraeger,
Alexander Gordeev, Thomas Richter, Sumanth Korikkar,
Sebastian Andrzej Siewior, Jiapeng Chong, kernel test robot,
linux-s390
On Fri, Feb 11, 2022 at 07:54:26AM +0100, Sven Schnelle wrote:
> Hi Yury,
>
> Yury Norov <yury.norov@gmail.com> writes:
>
> > cfset_all_start() calls cpumask_weight() to compare the weight of cpumask
> > with a given number. We can do it more efficiently with
> > cpumask_weight_{eq, ...} because conditional cpumask_weight may stop
> > traversing the cpumask earlier, as soon as condition is (or can't be) met.
> >
> > Signed-off-by: Yury Norov <yury.norov@gmail.com>
> > ---
> > arch/s390/kernel/perf_cpum_cf.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
> > index ee8707abdb6a..4d217f7f5ccf 100644
> > --- a/arch/s390/kernel/perf_cpum_cf.c
> > +++ b/arch/s390/kernel/perf_cpum_cf.c
> > @@ -975,7 +975,7 @@ static int cfset_all_start(struct cfset_request *req)
> > return -ENOMEM;
> > cpumask_and(mask, &req->mask, cpu_online_mask);
> > on_each_cpu_mask(mask, cfset_ioctl_on, &p, 1);
> > - if (atomic_read(&p.cpus_ack) != cpumask_weight(mask)) {
> > + if (!cpumask_weight_eq(mask, atomic_read(&p.cpus_ack))) {
> > on_each_cpu_mask(mask, cfset_ioctl_off, &p, 1);
> > rc = -EIO;
> > debug_sprintf_event(cf_dbg, 4, "%s CPUs missing", __func__);
>
> given that you're adding a bunch of these functions - gt,lt,eq and
> others, i wonder whether it makes sense to also add cpumask_weight_ne(),
> so one could just write:
>
> if (cpumask_weight_ne(mask, atomic_read(&p.cpus_ack))) {
> ...
> }
>
> ?
It will have 3 users in cpumask + 1 in nodemask. I have no strong opinion
whether we need it or not. Let's see what people say.
Thanks,
Yury
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <20220210224933.379149-1-yury.norov@gmail.com>
2022-02-10 22:49 ` [PATCH 39/49] arch/s390: replace cpumask_weight with cpumask_weight_eq where appropriate Yury Norov
2022-02-11 6:54 ` Sven Schnelle
2022-02-11 23:40 ` Yury Norov
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