diff options
Diffstat (limited to 'debian/patches-rt/0013-sched-rt-Use-cpumask_any-_distribute.patch')
| -rw-r--r-- | debian/patches-rt/0013-sched-rt-Use-cpumask_any-_distribute.patch | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/debian/patches-rt/0013-sched-rt-Use-cpumask_any-_distribute.patch b/debian/patches-rt/0013-sched-rt-Use-cpumask_any-_distribute.patch new file mode 100644 index 000000000..b190e58d4 --- /dev/null +++ b/debian/patches-rt/0013-sched-rt-Use-cpumask_any-_distribute.patch @@ -0,0 +1,121 @@ +From 0d3b4a8d9391d1eb1efb998bfcaff013a01466bf Mon Sep 17 00:00:00 2001 +From: Peter Zijlstra <peterz@infradead.org> +Date: Fri, 23 Oct 2020 12:12:10 +0200 +Subject: [PATCH 013/323] sched,rt: Use cpumask_any*_distribute() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz + +Replace a bunch of cpumask_any*() instances with +cpumask_any*_distribute(), by injecting this little bit of random in +cpu selection, we reduce the chance two competing balance operations +working off the same lowest_mask pick the same CPU. + +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + include/linux/cpumask.h | 6 ++++++ + kernel/sched/deadline.c | 6 +++--- + kernel/sched/rt.c | 6 +++--- + lib/cpumask.c | 18 ++++++++++++++++++ + 4 files changed, 30 insertions(+), 6 deletions(-) + +diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h +index f0d895d6ac39..383684e30f12 100644 +--- a/include/linux/cpumask.h ++++ b/include/linux/cpumask.h +@@ -199,6 +199,11 @@ static inline int cpumask_any_and_distribute(const struct cpumask *src1p, + return cpumask_next_and(-1, src1p, src2p); + } + ++static inline int cpumask_any_distribute(const struct cpumask *srcp) ++{ ++ return cpumask_first(srcp); ++} ++ + #define for_each_cpu(cpu, mask) \ + for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) + #define for_each_cpu_not(cpu, mask) \ +@@ -252,6 +257,7 @@ int cpumask_any_but(const struct cpumask *mask, unsigned int cpu); + unsigned int cpumask_local_spread(unsigned int i, int node); + int cpumask_any_and_distribute(const struct cpumask *src1p, + const struct cpumask *src2p); ++int cpumask_any_distribute(const struct cpumask *srcp); + + /** + * for_each_cpu - iterate over every cpu in a mask +diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c +index 5566f157640b..e64d378e4e87 100644 +--- a/kernel/sched/deadline.c ++++ b/kernel/sched/deadline.c +@@ -2012,8 +2012,8 @@ static int find_later_rq(struct task_struct *task) + return this_cpu; + } + +- best_cpu = cpumask_first_and(later_mask, +- sched_domain_span(sd)); ++ best_cpu = cpumask_any_and_distribute(later_mask, ++ sched_domain_span(sd)); + /* + * Last chance: if a CPU being in both later_mask + * and current sd span is valid, that becomes our +@@ -2035,7 +2035,7 @@ static int find_later_rq(struct task_struct *task) + if (this_cpu != -1) + return this_cpu; + +- cpu = cpumask_any(later_mask); ++ cpu = cpumask_any_distribute(later_mask); + if (cpu < nr_cpu_ids) + return cpu; + +diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c +index fdcce04913db..695526a54a89 100644 +--- a/kernel/sched/rt.c ++++ b/kernel/sched/rt.c +@@ -1766,8 +1766,8 @@ static int find_lowest_rq(struct task_struct *task) + return this_cpu; + } + +- best_cpu = cpumask_first_and(lowest_mask, +- sched_domain_span(sd)); ++ best_cpu = cpumask_any_and_distribute(lowest_mask, ++ sched_domain_span(sd)); + if (best_cpu < nr_cpu_ids) { + rcu_read_unlock(); + return best_cpu; +@@ -1784,7 +1784,7 @@ static int find_lowest_rq(struct task_struct *task) + if (this_cpu != -1) + return this_cpu; + +- cpu = cpumask_any(lowest_mask); ++ cpu = cpumask_any_distribute(lowest_mask); + if (cpu < nr_cpu_ids) + return cpu; + +diff --git a/lib/cpumask.c b/lib/cpumask.c +index fb22fb266f93..c3c76b833384 100644 +--- a/lib/cpumask.c ++++ b/lib/cpumask.c +@@ -261,3 +261,21 @@ int cpumask_any_and_distribute(const struct cpumask *src1p, + return next; + } + EXPORT_SYMBOL(cpumask_any_and_distribute); ++ ++int cpumask_any_distribute(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_distribute); +-- +2.43.0 + |