From d46031f40e0f7f7bf63914bb3f2e404ad3886ecd Mon Sep 17 00:00:00 2001 From: Raghavendra K T Date: Wed, 1 Mar 2023 17:49:03 +0530 Subject: [PATCH] sched/numa: use hash_32 to mix up PIDs accessing VMA before: last 6 bits of PID is used as index to store information about tasks accessing VMA's. after: hash_32 is used to take of cases where tasks are created over a period of time, and thus improve collision probability. Result: The patch series overall improves autonuma cost. Kernbench around more than 5% improvement and system time in mmtest autonuma showed more than 80% improvement Link: https://lkml.kernel.org/r/d5a9f75513300caed74e5c8570bba9317b963c2b.1677672277.git.raghavendra.kt@amd.com Signed-off-by: Raghavendra K T Suggested-by: Peter Zijlstra Cc: Bharata B Rao Cc: David Hildenbrand Cc: Disha Talreja Cc: Ingo Molnar Cc: Mel Gorman Cc: Mike Rapoport Signed-off-by: Andrew Morton --- include/linux/mm.h | 2 +- kernel/sched/fair.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index e05a878e186e..e249208f8fbe 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1691,7 +1691,7 @@ static inline void vma_set_access_pid_bit(struct vm_area_struct *vma) { unsigned int pid_bit; - pid_bit = current->pid % BITS_PER_LONG; + pid_bit = hash_32(current->pid, ilog2(BITS_PER_LONG)); if (vma->numab_state && !test_bit(pid_bit, &vma->numab_state->access_pids[1])) { __set_bit(pid_bit, &vma->numab_state->access_pids[1]); } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a962d4b60cd7..db6fc9d978ae 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2941,7 +2941,7 @@ static bool vma_is_accessed(struct vm_area_struct *vma) return true; pids = vma->numab_state->access_pids[0] | vma->numab_state->access_pids[1]; - return test_bit(current->pid % BITS_PER_LONG, &pids); + return test_bit(hash_32(current->pid, ilog2(BITS_PER_LONG)), &pids); } #define VMA_PID_RESET_PERIOD (4 * sysctl_numa_balancing_scan_delay)