diff options
author | Tommaso Cucinotta <tommaso.cucinotta@sssup.it> | 2016-08-14 17:27:07 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2016-09-05 14:29:43 +0300 |
commit | 8e1bc301aaf9f9a2d731bf8d50d549ac2dcfdab2 (patch) | |
tree | 8798854958a7f7cdba71e79015f694798d6a5857 /kernel/sched/cpudeadline.c | |
parent | 126b3b6842cc848fc9880e7816e0a8d743be51f1 (diff) |
sched/deadline: Make CPU heap faster avoiding real swaps on heapify
This change goes from heapify() ops done by swapping with parent/child
so that the item to fix moves along, to heapify() ops done by just
pulling the parent/child chain by 1 pos, then storing the item to fix
just at the end. On a non-trivial heapify(), this performs roughly half
stores wrt swaps.
This has been measured to achieve up to 10% of speed-up for cpudl_set()
calls, with a randomly generated workload of 1K,10K,100K random heap
insertions and deletions (75% cpudl_set() calls with is_valid=1 and
25% with is_valid=0), and randomly generated cpu IDs, with up to 256
CPUs, as measured on an Intel Core2 Duo.
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-3-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/cpudeadline.c')
-rw-r--r-- | kernel/sched/cpudeadline.c | 66 |
1 files changed, 45 insertions, 21 deletions
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index 0acb0d4e2fb7..0ace75a7a87b 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -31,48 +31,72 @@ static inline int right_child(int i) return (i << 1) + 2; } -static void cpudl_exchange(struct cpudl *cp, int a, int b) -{ - int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu; - - swap(cp->elements[a].cpu, cp->elements[b].cpu); - swap(cp->elements[a].dl , cp->elements[b].dl ); - - swap(cp->elements[cpu_a].idx, cp->elements[cpu_b].idx); -} - static void cpudl_heapify_down(struct cpudl *cp, int idx) { int l, r, largest; + int orig_cpu = cp->elements[idx].cpu; + u64 orig_dl = cp->elements[idx].dl; + + if (left_child(idx) >= cp->size) + return; + /* adapted from lib/prio_heap.c */ while(1) { + u64 largest_dl; l = left_child(idx); r = right_child(idx); largest = idx; + largest_dl = orig_dl; - if ((l < cp->size) && dl_time_before(cp->elements[idx].dl, - cp->elements[l].dl)) + if ((l < cp->size) && dl_time_before(orig_dl, + cp->elements[l].dl)) { largest = l; - if ((r < cp->size) && dl_time_before(cp->elements[largest].dl, - cp->elements[r].dl)) + largest_dl = cp->elements[l].dl; + } + if ((r < cp->size) && dl_time_before(largest_dl, + cp->elements[r].dl)) largest = r; + if (largest == idx) break; - /* Push idx down the heap one level and bump one up */ - cpudl_exchange(cp, largest, idx); + /* pull largest child onto idx */ + cp->elements[idx].cpu = cp->elements[largest].cpu; + cp->elements[idx].dl = cp->elements[largest].dl; + cp->elements[cp->elements[idx].cpu].idx = idx; idx = largest; } + /* actual push down of saved original values orig_* */ + cp->elements[idx].cpu = orig_cpu; + cp->elements[idx].dl = orig_dl; + cp->elements[cp->elements[idx].cpu].idx = idx; } static void cpudl_heapify_up(struct cpudl *cp, int idx) { - while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl, - cp->elements[idx].dl)) { - cpudl_exchange(cp, idx, parent(idx)); - idx = parent(idx); - } + int p; + + int orig_cpu = cp->elements[idx].cpu; + u64 orig_dl = cp->elements[idx].dl; + + if (idx == 0) + return; + + do { + p = parent(idx); + if (dl_time_before(orig_dl, cp->elements[p].dl)) + break; + /* pull parent onto idx */ + cp->elements[idx].cpu = cp->elements[p].cpu; + cp->elements[idx].dl = cp->elements[p].dl; + cp->elements[cp->elements[idx].cpu].idx = idx; + idx = p; + } while (idx != 0); + /* actual push up of saved original values orig_* */ + cp->elements[idx].cpu = orig_cpu; + cp->elements[idx].dl = orig_dl; + cp->elements[cp->elements[idx].cpu].idx = idx; } static void cpudl_heapify(struct cpudl *cp, int idx) |