From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBD141865A; Fri, 28 Jun 2024 11:20:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719573658; cv=none; b=QtDAokJbUkOzeAaSQaVTuTT+Rxb3ENKI5vh8kxngEULbjewk0xyYWxRf57fSixpjLEEMWed2ZuvoTQSAtDyx6806xFYN93pnm2WhgxokZsEwsRxvZ+u5HTBIdW4NpbM3lrxaGHYJSuxjnpgxC/TOymINuAyYM88+POQbpBfZscI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719573658; c=relaxed/simple; bh=gQeYH+LG8291IRJvEG/1gi0BWNeiPp2grvRZNYZzpOs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ItDIYOMJra87GW4WRVzAWXl+nSw3e+962k53EbmR/TRoLaavYm+WwyMqNV8RJrrVzdUMl1YPpZOP4N5qcfvuvO2u4VlZMfde4P3JXl/eEXZS8XrBzZK/2w75vvbrhmcTCGkfjgFtdpmh/TQmY8fk/22ne7Za8DpAE0TnNrUklMM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tR2BmwAe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tR2BmwAe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D509BC116B1; Fri, 28 Jun 2024 11:20:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719573658; bh=gQeYH+LG8291IRJvEG/1gi0BWNeiPp2grvRZNYZzpOs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tR2BmwAebw8/TRARIoz2TlXoGi4+WTnplk7PaCbcJOuu7t/Xl5eGVJgBTFl3xq2A4 9f/Hw5mPB1P2pNkTdjR27vTBdPH6pA35j2R/gSqo8KWMTREJb2vLxndLhIscjERriW LtLPvECmB+RVriTMRBQDsHEjWDuqd1mksfUlw6/UFSu6HSn12qOgXy+DUl6w3qmpqb 4xSLzgZCr8rJ5q8adbSRQ7WX/UpK+xt0C9PgvnDhrTeVALat1KGv5l1gUCKKwGa5iF 6IEljwao4XARLmKWZ1Fp/fIut0MFe8mu5HUVU4fUgIZce+SK7DBiC97T4ulTaQ4gS0 ilErjw0iGoIfA== Date: Fri, 28 Jun 2024 13:20:55 +0200 From: Frederic Weisbecker To: "Paul E. McKenney" Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org Subject: Re: [PATCH rcu 3/6 v2] rcu/exp: Remove superfluous full memory barrier upon first EQS snapshot Message-ID: References: <81f4e616-8125-4934-a8e2-fd5beae90995@paulmck-laptop> <20240604222652.2370998-3-paulmck@kernel.org> <4a11271a-d873-4f1c-87e6-38874e38ac13@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4a11271a-d873-4f1c-87e6-38874e38ac13@paulmck-laptop> Le Thu, Jun 27, 2024 at 11:53:29AM -0700, Paul E. McKenney a écrit : > On Thu, Jun 27, 2024 at 01:36:58PM +0200, Frederic Weisbecker wrote: > > When the grace period kthread checks the extended quiescent state > > counter of a CPU, full ordering is necessary to ensure that either: > > Just to make sure that I understand... > > I need to replace these commits in -rcu: > > da979d0162fc6 rcu: Remove full ordering on second EQS snapshot > 6411f4185f657 rcu: Remove superfluous full memory barrier upon first EQS snapshot > dec56ca5f1c34 rcu/exp: Remove superfluous full memory barrier upon first EQS snapshot > > With these three patches, and keep these three commits as they are? > > d43a302fc08a5 rcu: Remove full memory barrier on boot time eqs sanity check > b1c36aa90cbf1 rcu: Remove full memory barrier on RCU stall printout > 64d68f1d53f77 rcu/exp: Remove redundant full memory barrier at the end of GP Exactly! Those were the precisions I forgot to mention. Thanks.