From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755233AbcESQCt (ORCPT ); Thu, 19 May 2016 12:02:49 -0400 Received: from ms01.sssup.it ([193.205.80.99]:47827 "EHLO sssup.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755128AbcESQCq (ORCPT ); Thu, 19 May 2016 12:02:46 -0400 From: Tommaso Cucinotta To: Luca Abeni , Juri Lelli , Peter Zijlstra , Ingo Molnar Cc: linux-kernel@vger.kernel.org, Tommaso Cucinotta Subject: [RFC PATCH 3/4] Make deadline max-heap faster avoiding real swaps on heapify ops. Date: Thu, 19 May 2016 18:02:11 +0200 Message-Id: <1463673732-944-4-git-send-email-tommaso.cucinotta@sssup.it> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1463673732-944-1-git-send-email-tommaso.cucinotta@sssup.it> References: <1463673732-944-1-git-send-email-tommaso.cucinotta@sssup.it> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --- kernel/sched/cpudeadline.c | 114 +++++++++++++++++++++++++++------------------ 1 file changed, 69 insertions(+), 45 deletions(-) diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index 3c42702..60f933a 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -31,60 +31,82 @@ 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(cp->elements[idx].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_change_key(struct cpudl *cp, int idx, u64 new_dl) +static void cpudl_heapify(struct cpudl *cp, int idx) { WARN_ON(idx == IDX_INVALID || !cpu_present(idx)); + if (idx == IDX_INVALID) + return; - if (dl_time_before(new_dl, cp->elements[idx].dl)) { - cp->elements[idx].dl = new_dl; - cpudl_heapify_down(cp, idx); - } else { - cp->elements[idx].dl = new_dl; + if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl, cp->elements[idx].dl)) { cpudl_heapify_up(cp, idx); + } else { + cpudl_heapify_down(cp, idx); } } @@ -153,28 +175,30 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid) */ goto out; } - new_cpu = cp->elements[cp->size - 1].cpu; - cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl; - cp->elements[old_idx].cpu = new_cpu; cp->size--; - cp->elements[new_cpu].idx = old_idx; cp->elements[cpu].idx = IDX_INVALID; - cpudl_heapify_up(cp, old_idx); - cpumask_set_cpu(cpu, cp->free_cpus); - cpudl_heapify_down(cp, old_idx); - - goto out; - } + if (old_idx != cp->size) { + new_cpu = cp->elements[cp->size].cpu; + cp->elements[old_idx].dl = cp->elements[cp->size].dl; + cp->elements[old_idx].cpu = new_cpu; + cp->elements[new_cpu].idx = old_idx; + cpudl_heapify(cp, old_idx); + } - if (old_idx == IDX_INVALID) { - int size1 = cp->size++; - cp->elements[size1].dl = dl; - cp->elements[size1].cpu = cpu; - cp->elements[cpu].idx = size1; - cpudl_heapify_up(cp, size1); - cpumask_clear_cpu(cpu, cp->free_cpus); + cpumask_set_cpu(cpu, cp->free_cpus); } else { - cpudl_change_key(cp, old_idx, dl); + if (old_idx == IDX_INVALID) { + int size1 = cp->size++; + cp->elements[size1].dl = dl; + cp->elements[size1].cpu = cpu; + cp->elements[cpu].idx = size1; + cpudl_heapify_up(cp, size1); + + cpumask_clear_cpu(cpu, cp->free_cpus); + } else { + cp->elements[old_idx].dl = dl; + cpudl_heapify(cp, old_idx); + } } out: -- 2.7.4