From nobody Sat Feb 7 15:10:19 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 32C4DC77B7A for ; Fri, 2 Jun 2023 19:05:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237141AbjFBTFJ (ORCPT ); Fri, 2 Jun 2023 15:05:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237115AbjFBTFD (ORCPT ); Fri, 2 Jun 2023 15:05:03 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45C211B7 for ; Fri, 2 Jun 2023 12:04:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685732659; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=lJAFxNimyhgGkmw8GXkGsiBNva5tBIiiepv3OQs0cGk=; b=AgYcQ6l/D00LoQZ/P/17iIEZ64fZTmBETs1LUX4SoUWh0jj//c526JYE+fLO9wOmOYx9/4 /KceDumZyikaIc9rJG2Bn7FXcb54rcWl79wREwF5/ykAsrf+PML5g+YJvqr+cu9vikFMRA L58Y3LznhmfcOD/XMuNslvmNUkgN/yM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-504-gCOX5Fs8O-Gvp5nPcrtFrw-1; Fri, 02 Jun 2023 15:04:08 -0400 X-MC-Unique: gCOX5Fs8O-Gvp5nPcrtFrw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6D3998007CE; Fri, 2 Jun 2023 19:04:06 +0000 (UTC) Received: from tpad.localdomain (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3891EC0297C; Fri, 2 Jun 2023 19:04:06 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id 1D840403BFA58; Fri, 2 Jun 2023 16:03:42 -0300 (-03) Message-ID: <20230602190115.545766386@redhat.com> User-Agent: quilt/0.67 Date: Fri, 02 Jun 2023 15:58:00 -0300 From: Marcelo Tosatti To: Christoph Lameter Cc: Aaron Tomlin , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vlastimil Babka , Michal Hocko , Marcelo Tosatti Subject: [PATCH v2 3/3] mm/vmstat: do not refresh stats for nohz_full CPUs References: <20230602185757.110910188@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The interruption caused by queueing work on nohz_full CPUs=20 is undesirable for certain aplications. Fix by not refreshing per-CPU stats of nohz_full CPUs.=20 Signed-off-by: Marcelo Tosatti --- v2: opencode schedule_on_each_cpu (Michal Hocko) Index: linux-vmstat-remote/mm/vmstat.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-vmstat-remote.orig/mm/vmstat.c +++ linux-vmstat-remote/mm/vmstat.c @@ -1881,8 +1881,13 @@ int vmstat_refresh(struct ctl_table *tab void *buffer, size_t *lenp, loff_t *ppos) { long val; - int err; int i; + int cpu; + struct work_struct __percpu *works; + + works =3D alloc_percpu(struct work_struct); + if (!works) + return -ENOMEM; =20 /* * The regular update, every sysctl_stat_interval, may come later @@ -1896,9 +1901,24 @@ int vmstat_refresh(struct ctl_table *tab * transiently negative values, report an error here if any of * the stats is negative, so we know to go looking for imbalance. */ - err =3D schedule_on_each_cpu(refresh_vm_stats); - if (err) - return err; + cpus_read_lock(); + for_each_online_cpu(cpu) { + struct work_struct *work; + + if (cpu_is_isolated(cpu)) + continue; + work =3D per_cpu_ptr(works, cpu); + INIT_WORK(work, refresh_vm_stats); + schedule_work_on(cpu, work); + } + + for_each_online_cpu(cpu) { + if (cpu_is_isolated(cpu)) + continue; + flush_work(per_cpu_ptr(works, cpu)); + } + cpus_read_unlock(); + free_percpu(works); for (i =3D 0; i < NR_VM_ZONE_STAT_ITEMS; i++) { /* * Skip checking stats known to go negative occasionally.