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 85C69C19F2B for ; Fri, 29 Jul 2022 07:01:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234648AbiG2HBr (ORCPT ); Fri, 29 Jul 2022 03:01:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233965AbiG2HBk (ORCPT ); Fri, 29 Jul 2022 03:01:40 -0400 Received: from polaris.svanheule.net (polaris.svanheule.net [IPv6:2a00:c98:2060:a004:1::200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 467121F2E7 for ; Fri, 29 Jul 2022 00:01:39 -0700 (PDT) Received: from terra.. (unknown [IPv6:2a02:a03f:eaf9:8401:aa9f:5d01:1b2a:e3cd]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: sander@svanheule.net) by polaris.svanheule.net (Postfix) with ESMTPSA id 2E4B4302C2D; Fri, 29 Jul 2022 09:01:33 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=svanheule.net; s=mail1707; t=1659078093; 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=dkZvhTljDkGb52uJmlQoon5W3jFZ8oxGweLeMELnqoE=; b=ZMQkVIoXQOJk8Y93zuFIa0n2qIroQmr+imRwGxGnln0iMh0WotiSDe69Pnhnx9ayWvU5MN aHSsL7VoWEI7IvB6fKO5UrULKGDuESLPUAppfWF28npyux+Epf3em5Wx/u5MX0qDxSO7G/ iW6NWsoXStp/w338zafz7Lz400rR2m6Xs1zRPW2AAdtXdBEfa5RlXJXzlGUSnTs7v2Ou76 9MgTTO1pWHLmldVkKckv7CsVbGTI0T1WMQHfoRdSOLqHZcxisU6cOb1RC5XMWPvVjc3dEV SRRTCXkATH6S/lBgjKGcXNbEk8xmysva30fkXGjJRpgrgn3h6Z0xqveYkk+8fg== From: Sander Vanheule To: linux-kernel@vger.kernel.org, Andrew Morton Cc: Andy Shevchenko , Brendan Higgins , Dave Hansen , David Gow , Borislav Petkov , Greg Kroah-Hartman , "H . Peter Anvin" , Ingo Molnar , =?UTF-8?q?Ma=C3=ADra=20Canal?= , Marco Elver , Peter Zijlstra , Thomas Gleixner , Valentin Schneider , Yury Norov , Sander Vanheule Subject: [PATCH v5 2/5] cpumask: add UP optimised for_each_*_cpu versions Date: Fri, 29 Jul 2022 09:01:19 +0200 Message-Id: X-Mailer: git-send-email 2.37.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On uniprocessor builds, the following loops will always run over a mask that contains one enabled CPU (cpu0): - for_each_possible_cpu - for_each_online_cpu - for_each_present_cpu Provide uniprocessor-specific macros for these loops, that always run exactly once, instead of just relying on for_each_cpu() to provide this optimisation. Signed-off-by: Sander Vanheule Acked-by: Yury Norov Cc: Andy Shevchenko Cc: Borislav Petkov Cc: Dave Hansen Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Marco Elver Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Valentin Schneider --- Changes since v4: - Move patch forward in series - Add Yury's Acked-by include/linux/cpumask.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index fe29ac7cc469..533612770bc0 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -811,9 +811,16 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS); /* First bits of cpu_bit_bitmap are in fact unset. */ #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0]) +#if NR_CPUS == 1 +/* Uniprocessor: the possible/online/present masks are always "1" */ +#define for_each_possible_cpu(cpu) for ((cpu) = 0; (cpu) < 1; (cpu)++) +#define for_each_online_cpu(cpu) for ((cpu) = 0; (cpu) < 1; (cpu)++) +#define for_each_present_cpu(cpu) for ((cpu) = 0; (cpu) < 1; (cpu)++) +#else #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask) #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask) #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask) +#endif /* Wrappers for arch boot code to manipulate normally-constant masks */ void init_cpu_present(const struct cpumask *src); -- 2.37.1