From mboxrd@z Thu Jan 1 00:00:00 1970 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 B0927C43219 for ; Tue, 22 Nov 2022 19:31:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234804AbiKVTbO (ORCPT ); Tue, 22 Nov 2022 14:31:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234786AbiKVTbJ (ORCPT ); Tue, 22 Nov 2022 14:31:09 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4405690580 for ; Tue, 22 Nov 2022 11:30:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669145411; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zSYjp+tSNrVSXI+gcTD2+vnKTaoJtRYmv4jLOiB9aTk=; b=Rj7zYd9sX37WDqapEFV0pXGQtt5+P+0ASTSLUcILy0kzdaLWZNSdd4u5pDLjIgMbERvh44 k1Oe0TryM+9RAK5jNbuz69gnWvvoeajybO0zb7WnJZ0I2UI0met9X+mk7nwZ6YSzwGVmit p7jQZEFbo5HNhLSoY5idXhRqa6hyphU= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-195-PEED_0QJOSOISy9CPCxUwQ-1; Tue, 22 Nov 2022 14:30:10 -0500 X-MC-Unique: PEED_0QJOSOISy9CPCxUwQ-1 Received: by mail-wm1-f69.google.com with SMTP id h9-20020a1c2109000000b003cfd37aec58so8516285wmh.1 for ; Tue, 22 Nov 2022 11:30:10 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=zSYjp+tSNrVSXI+gcTD2+vnKTaoJtRYmv4jLOiB9aTk=; b=RilhoFZ1OgHRw7pFXrl0yVmXTZKGdxyW3V3WxmEJrfaLmK4DNme8Jec07LtFsML9Bj LwsbkyjkM2isXPrhbbb5EnJFQX7cexHNb9M+QAykL+5HSFOmkutyDTi4p4Rq4QHhHS48 q6jl4q4+2Xp0UgAvJqWe3OWAxla5jldo0rT9iY28xvjrI/zkNPw+3ofdCPwNDlbm6Guw P7r5jUzxuiIep3iW6X42KE5R4y54rBATRhUVmkBJesEurMNeTrvK3xnGUI+x9VCyYXw0 whXABf/3BJw9oIroMOsRU7YqH29w/ef+bsiAxoYAXuXCe6tcNuZyEL4689HSAW5i+1rW PV1A== X-Gm-Message-State: ANoB5pkTEyQWVZmTCxIXY5uyk8nhZ03ywEnafzrnAf4/7i3rYelY1b38 jnr9aSjJdVbh/18mAaqHZsZBhreOEQYRBS1VkkW273B/HGK8HqseQVL1l1qaxtMGRG3yPuCwHsP uw2/GtQkWZjfZsN4J8CSajAdTnnHYjgfMOrNXmVb07DOXqVh35LUfr5/rm97KuWYMTHcjtfI1zO ok X-Received: by 2002:a05:600c:6545:b0:3cf:baef:e92a with SMTP id dn5-20020a05600c654500b003cfbaefe92amr5385800wmb.178.1669145408533; Tue, 22 Nov 2022 11:30:08 -0800 (PST) X-Google-Smtp-Source: AA0mqf6/JepPLrHqvTtEnrWsWTg0oO86adc7JxOwP62o9Myj55cwEh7sO9iqnA92E83yo76GdpZgpw== X-Received: by 2002:a05:600c:6545:b0:3cf:baef:e92a with SMTP id dn5-20020a05600c654500b003cfbaefe92amr5385782wmb.178.1669145408300; Tue, 22 Nov 2022 11:30:08 -0800 (PST) Received: from vschneid.remote.csb ([154.57.232.159]) by smtp.gmail.com with ESMTPSA id r14-20020adff10e000000b002366553eca7sm4173682wro.83.2022.11.22.11.30.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Nov 2022 11:30:07 -0800 (PST) From: Valentin Schneider To: linux-kernel@vger.kernel.org Cc: Tejun Heo , Lai Jiangshan , Peter Zijlstra , Frederic Weisbecker , Juri Lelli , Phil Auld , Marcelo Tosatti Subject: [PATCH v5 3/5] workqueue: Make too_many_workers() return the worker excess Date: Tue, 22 Nov 2022 19:29:35 +0000 Message-Id: <20221122192937.2386494-4-vschneid@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20221122192937.2386494-1-vschneid@redhat.com> References: <20221122192937.2386494-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Later patches will need the logic implemented within too_many_workers() to get the amount of workers to delete. Rather than duplicate the logic, rework too_many_workers() to return the count of workers to delete - its return value can be used as a boolean value, so no change in behaviour intended. The function currently returns true when (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy thus, the desired number of idle workers is expressed by (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO == nr_busy - 1 IOW nr_idle == ((nr_busy - 1) / MAX_IDLE_WORKERS_RATIO) + 2 MAX_IDLE_WORKERS_RATIO being a compile-time power of 2, we can leave that as a division. While at it, rename too_many_workers() to worker_cull_count(). Signed-off-by: Valentin Schneider --- kernel/workqueue.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 8185a42848c50..4fc8085f3fe17 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -816,14 +816,20 @@ static bool need_to_create_worker(struct worker_pool *pool) return need_more_worker(pool) && !may_start_working(pool); } -/* Do we have too many workers and should some go away? */ -static bool too_many_workers(struct worker_pool *pool) +/* How many idle workers should we get rid of, if any? */ +static unsigned int worker_cull_count(struct worker_pool *pool) { bool managing = pool->flags & POOL_MANAGER_ACTIVE; int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ int nr_busy = pool->nr_workers - nr_idle; - return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; + lockdep_assert_held(&pool->lock); + + /* + * We keep at least 2 spare idle workers, but overall aim to keep at + * most (1 / MAX_IDLE_WORKERS_RATIO) workers idle. + */ + return max(0, nr_idle - 2 - ((nr_busy - 1) / MAX_IDLE_WORKERS_RATIO)); } /* @@ -1806,7 +1812,7 @@ static void worker_enter_idle(struct worker *worker) /* idle_list is LIFO */ list_add(&worker->entry, &pool->idle_list); - if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) + if (worker_cull_count(pool) && !timer_pending(&pool->idle_timer)) mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); /* Sanity check nr_running. */ @@ -2025,7 +2031,7 @@ static void idle_worker_timeout(struct timer_list *t) raw_spin_lock_irq(&pool->lock); - while (too_many_workers(pool)) { + while (worker_cull_count(pool)) { struct worker *worker; unsigned long expires; -- 2.31.1