From patchwork Fri Nov 13 14:02:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 11903685 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0A4DC388F7 for ; Fri, 13 Nov 2020 14:29:27 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9941620715 for ; Fri, 13 Nov 2020 14:29:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="E2iz2Uqq"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="QExJdAkf"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="ZH/Vk7tQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9941620715 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:Subject:To:From:Date: Message-Id:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:List-Owner; bh=uY3gC12Opafa6Ml5YTPObMJY6CyskqrUj7B2a6pzjoE=; b=E2iz2Uqqev3Em3VaKyOcJ/pDC lIu/N16pOJmNSLMmWySBYHFBgKG9UHV7NTgJQbikgqDB08D0qBPiMKJU3Dydi0/5p8H4dbch4snIl jmgmOLAit5hyGTbLjuBz2dUK2WvwthUIqpNwPLutu6Ejv6TcUAVpaD22br37HtrUvApyOPM+y1083 zqX0XtJNQad6biKZ6YbeZBEC1DK/7H6Cf9lg99Jlpi0lqW57MziAcXYEXDNYGnvfjDQpejOzqK315 b0o94Ysu97bbH35fA5LXPS6arTD80QH7mwh/sVsUOEuuPnHsdgpU12q5mlpW7drDGHuQHpw047htz XSC8U07Fg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kda3J-0007xn-58; Fri, 13 Nov 2020 14:27:49 +0000 Received: from galois.linutronix.de ([193.142.43.55]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kda0C-0006Oa-EZ; Fri, 13 Nov 2020 14:24:45 +0000 Message-Id: <20201113141734.660734753@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1605277475; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=74sFpsXIvDvQMapG5Pk7sHOAlnsFK2WUN0Z1OZznnHw=; b=QExJdAkfPvDBwGkQeFoFlNrm4JXX8p/fB5MMB0uuiSdagTfMsaVZdXy9G9GBW/pJGeMMhF v2D/rBvzOwa2UI3CLJLGXLp9JbHgnTpigxMvChKOaxUXPDJjvXKV29RXNoCJIM02ssvFoi fAJSXNYmXPoUeZuLpHQOomjC1BPe/vo61ydVsoo44kvswfSQrHrQmBcsQcqiTK7Ntdx/Py xO9hHJhmudd3p/qulzbc5q7cT/UiquVfGqe3gjkh05B6zglrlDkMWKu7yjfwROgKAs1IpI nuG8KFPBmSSMRxwWYbHo6AVIPTGAZ3rfXubf5JvX0QsRdE7Y3QWJo63Q754Rlw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1605277475; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=74sFpsXIvDvQMapG5Pk7sHOAlnsFK2WUN0Z1OZznnHw=; b=ZH/Vk7tQMxbpxGEvsAm2QgjQRjaIccewrZgX7RMwhumzkvb9r1Yzrpuqulq+HX3l7OQ5+E wyyqEioCc993+MDA== Date: Fri, 13 Nov 2020 15:02:24 +0100 From: Thomas Gleixner To: LKML Subject: [patch 17/19] softirq: Replace barrier() with cpu_relax() in tasklet_unlock_wait() References: <20201113140207.499353218@linutronix.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201113_092436_810334_32BF988F X-CRM114-Status: GOOD ( 10.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , Rich Felker , Catalin Marinas , Paul McKenney , Arnd Bergmann , linux-sh@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Frederic Weisbecker , Valentin Schneider , Jeff Dike , Russell King , Yoshinori Sato , "James E.J. Bottomley" , linux-parisc@vger.kernel.org, Helge Deller , linux-um@lists.infradead.org, Will Deacon , Sebastian Andrzej Siewior , linux-arm-kernel@lists.infradead.org, Anton Ivanov Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org A barrier() in a tight loop which waits for something to happen on a remote CPU is a pointless exercise. Replace it with cpu_relax() which allows HT siblings to make progress. Signed-off-by: Thomas Gleixner --- include/linux/interrupt.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -668,7 +668,8 @@ static inline void tasklet_unlock(struct static inline void tasklet_unlock_wait(struct tasklet_struct *t) { - while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); } + while (test_bit(TASKLET_STATE_RUN, &(t)->state)) + cpu_relax(); } #else #define tasklet_trylock(t) 1