Messages in this thread Patch in this message | | | From | Qais Yousef <> | Subject | [PATCH 2/4] cpumask: Make cpumask_any() truly random | Date | Tue, 14 Apr 2020 16:05:54 +0100 |
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Commit 46a87b3851f0 ("sched/core: Distribute tasks within affinity masks") added a new cpumask_any_and_distribute() which truly returns a random cpu within the mask.
Previous patch renamed the function to cpumask_any_and(), so that old users can take advantage of the new randomness behavior.
Build up on that, and let cpumask_any() truly random too by re-using the logic from cpumask_any_and().
Signed-off-by: Qais Yousef <qais.yousef@arm.com> CC: Juri Lelli <juri.lelli@redhat.com> CC: Vincent Guittot <vincent.guittot@linaro.org> CC: Dietmar Eggemann <dietmar.eggemann@arm.com> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ben Segall <bsegall@google.com> CC: Mel Gorman <mgorman@suse.de> CC: Andrew Morton <akpm@linux-foundation.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Yury Norov <yury.norov@gmail.com> CC: Paul Turner <pjt@google.com> CC: Alexey Dobriyan <adobriyan@gmail.com> CC: Josh Don <joshdon@google.com> CC: Pavan Kondeti <pkondeti@codeaurora.org> CC: linux-kernel@vger.kernel.org --- include/linux/cpumask.h | 14 ++++++-------- lib/cpumask.c | 24 ++++++++++++++++++++++++ 2 files changed, 30 insertions(+), 8 deletions(-)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index e4d6d140a67c..7fb25d256043 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -194,6 +194,11 @@ static inline unsigned int cpumask_local_spread(unsigned int i, int node) return 0; } +static inline int cpumask_any(const struct cpumask *src1p) +{ + return 0; +} + static inline int cpumask_any_and(const struct cpumask *src1p, const struct cpumask *src2p) { @@ -251,6 +256,7 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp) int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *); int cpumask_any_but(const struct cpumask *mask, unsigned int cpu); unsigned int cpumask_local_spread(unsigned int i, int node); +int cpumask_any(const struct cpumask *srcp); int cpumask_any_and(const struct cpumask *src1p, const struct cpumask *src2p); /** @@ -600,14 +606,6 @@ static inline void cpumask_copy(struct cpumask *dstp, bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits); } -/** - * cpumask_any - pick a "random" cpu from *srcp - * @srcp: the input cpumask - * - * Returns >= nr_cpu_ids if no cpus set. - */ -#define cpumask_any(srcp) cpumask_first(srcp) - /** * cpumask_first_and - return the first cpu from *srcp1 & *srcp2 * @src1p: the first input diff --git a/lib/cpumask.c b/lib/cpumask.c index b527a153b023..bcac63e45374 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -259,3 +259,27 @@ int cpumask_any_and(const struct cpumask *src1p, const struct cpumask *src2p) return next; } EXPORT_SYMBOL(cpumask_any_and); + +/** + * cpumask_any - pick a "random" cpu from *srcp + * @srcp: the input cpumask + * + * Returns >= nr_cpu_ids if no cpus set. + */ +int cpumask_any(const struct cpumask *srcp) +{ + int next, prev; + + /* NOTE: our first selection will skip 0. */ + prev = __this_cpu_read(distribute_cpu_mask_prev); + + next = cpumask_next(prev, srcp); + if (next >= nr_cpu_ids) + next = cpumask_first(srcp); + + if (next < nr_cpu_ids) + __this_cpu_write(distribute_cpu_mask_prev, next); + + return next; +} +EXPORT_SYMBOL(cpumask_any); -- 2.17.1
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