From nobody Fri Jan 2 15:45:01 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A2F6CD691F for ; Tue, 10 Oct 2023 09:44:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230043AbjJJJoG (ORCPT ); Tue, 10 Oct 2023 05:44:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229929AbjJJJnw (ORCPT ); Tue, 10 Oct 2023 05:43:52 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9420794; Tue, 10 Oct 2023 02:43:49 -0700 (PDT) Date: Tue, 10 Oct 2023 09:43:47 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1696931027; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XxPg9S3TxC7Oe6LoTvfsQog36rfpA0VPwIyI0YgTQqE=; b=2qDdY6dJtn4ba7taWCc4oK4xihwnGBr15P1HnhbYMeBiqWBHawfRu3+tqImEU/e8rjYy16 LICT0frI/s+lwkiLnSFF6ZjgRKy+h1qFCZ1L9WcNVSaioRnvSDyA8CeVpnMLEQkgwgD4e9 lX3AFTRa459mZUFbwzLeU4L7S3fUUtvBVnf/1AhmOfnhn8nBKCnPn9l/XLA1zKbYZyenlv SFx/DeQazr2VciiSVIa8oL9AKiV0eMuQk7IqSOeV31qnLM622MnwHEJxviocQgCluQa0kK e2EZwsWcaLkY2J6TaEB9xSa+BL6NqkDDYTlSbm8NgTBvj3zQKmXyMA/cM6chJw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1696931027; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XxPg9S3TxC7Oe6LoTvfsQog36rfpA0VPwIyI0YgTQqE=; b=FRJ2jbpeZ7po9R39aK6oIFH68pHBlgEPtNYDo2RlcQOTy6LQSp5E8s9m6TavqIxZl985O7 v04D3iK3ASh/UQBg== From: "tip-bot2 for Mel Gorman" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/numa: Complete scanning of partial VMAs regardless of PID activity Cc: Mel Gorman , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20231010083143.19593-6-mgorman@techsingularity.net> References: <20231010083143.19593-6-mgorman@techsingularity.net> MIME-Version: 1.0 Message-ID: <169693102718.3135.17849414903798441575.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: 8dd6cab1a5e96f1e4ac4969d2e5575082caab20d Gitweb: https://git.kernel.org/tip/8dd6cab1a5e96f1e4ac4969d2e5575082= caab20d Author: Mel Gorman AuthorDate: Tue, 10 Oct 2023 09:31:42 +01:00 Committer: Ingo Molnar CommitterDate: Tue, 10 Oct 2023 11:10:01 +02:00 sched/numa: Complete scanning of partial VMAs regardless of PID activity NUMA Balancing skips VMAs when the current task has not trapped a NUMA fault within the VMA. If the VMA is skipped then mm->numa_scan_offset advances and a task that is trapping faults within the VMA may never fully update PTEs within the VMA. Force tasks to update PTEs for partially scanned PTEs. The VMA will be tagged for NUMA hints by some task but this removes some of the benefit of tracking PID activity within a VMA. A follow-on patch will mitigate this problem. The test cases and machines evaluated did not trigger the corner case so the performance results are neutral with only small changes within the noise from normal test-to-test variance. However, the next patch makes the corner case easier to trigger. Signed-off-by: Mel Gorman Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20231010083143.19593-6-mgorman@techsingular= ity.net --- include/linux/sched/numa_balancing.h | 1 + include/trace/events/sched.h | 3 ++- kernel/sched/fair.c | 18 +++++++++++++++--- 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/include/linux/sched/numa_balancing.h b/include/linux/sched/num= a_balancing.h index c127a15..7dcc0bd 100644 --- a/include/linux/sched/numa_balancing.h +++ b/include/linux/sched/numa_balancing.h @@ -21,6 +21,7 @@ enum numa_vmaskip_reason { NUMAB_SKIP_INACCESSIBLE, NUMAB_SKIP_SCAN_DELAY, NUMAB_SKIP_PID_INACTIVE, + NUMAB_SKIP_IGNORE_PID, }; =20 #ifdef CONFIG_NUMA_BALANCING diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index d82a04d..bfc07c1 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -670,7 +670,8 @@ DEFINE_EVENT(sched_numa_pair_template, sched_swap_numa, EM( NUMAB_SKIP_SHARED_RO, "shared_ro" ) \ EM( NUMAB_SKIP_INACCESSIBLE, "inaccessible" ) \ EM( NUMAB_SKIP_SCAN_DELAY, "scan_delay" ) \ - EMe(NUMAB_SKIP_PID_INACTIVE, "pid_inactive" ) + EM( NUMAB_SKIP_PID_INACTIVE, "pid_inactive" ) \ + EMe(NUMAB_SKIP_IGNORE_PID, "ignore_pid_inactive" ) =20 /* Redefine for export. */ #undef EM diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ce36969..ab79013 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3113,7 +3113,7 @@ static void reset_ptenuma_scan(struct task_struct *p) p->mm->numa_scan_offset =3D 0; } =20 -static bool vma_is_accessed(struct vm_area_struct *vma) +static bool vma_is_accessed(struct mm_struct *mm, struct vm_area_struct *v= ma) { unsigned long pids; /* @@ -3126,7 +3126,19 @@ static bool vma_is_accessed(struct vm_area_struct *v= ma) return true; =20 pids =3D vma->numab_state->pids_active[0] | vma->numab_state->pids_active= [1]; - return test_bit(hash_32(current->pid, ilog2(BITS_PER_LONG)), &pids); + if (test_bit(hash_32(current->pid, ilog2(BITS_PER_LONG)), &pids)) + return true; + + /* + * Complete a scan that has already started regardless of PID access, or + * some VMAs may never be scanned in multi-threaded applications: + */ + if (mm->numa_scan_offset > vma->vm_start) { + trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_IGNORE_PID); + return true; + } + + return false; } =20 #define VMA_PID_RESET_PERIOD (4 * sysctl_numa_balancing_scan_delay) @@ -3270,7 +3282,7 @@ static void task_numa_work(struct callback_head *work) } =20 /* Do not scan the VMA if task has not accessed */ - if (!vma_is_accessed(vma)) { + if (!vma_is_accessed(mm, vma)) { trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE); continue; }