From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 123281FA15B for ; Mon, 2 Dec 2024 14:51:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733151081; cv=none; b=FQZ4yMAPwcYL3sX47g4r+qvEwS7R78tlBRXGSHhQdWXk4pkjd9MAClZSz+EMo7Gbb+Z8gNeFSVFOAKPuEt9ucAKwj7YvVNqXlzQF3BwaJDrBLwoL1z+AyLNY5Vpw4Cti7fjWmZqQub59Wl9rP4DzFT/YpjsxYU5TAlQTu6QbEzc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733151081; c=relaxed/simple; bh=0xCNWCz7YLg1GqxfHrrvoPZkYFFTrobY0Zep6qf3LXk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=k5lRkK8t8Is0d4tflL50hbj/9GRXYt3NsiGUZ83/MlesCfKZE8wdJD2G8d7DfnUiHAw7Pcq+I/JV2ONEb8kl7q4sSsdHG6jYFXGIHCJWaRj4G1NJRlRlGpNuoVpB6xGpRsNHE4kIG7VbKeAqdQkHipQ+PPfkwDNL4fgTm+b8gpg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=c1OLPR17; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="c1OLPR17" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=Gz6AcXAZa2rLVWcMxOUDJFVEMIYUf2TndHTnTlXHpBg=; b=c1OLPR17uWHgyPCFn/4/eFDrez HgjqoIxY8tij97eQlaw8d1ycy3/wruoiFHmhWDMV2JaNqRI+UzKesQ975mzUbR7MR+dwhrVTTIKsj je35AeF0KQqZJhuhojF6UQFk1SqTJEUkLLIae+S5RGdG8wzjA9NQi3y74bSPs2T+PZXC1YtJTBWRt aBkIYbR0KjIIrJnIvVjeDBBe8BJ1V4efEdF1OSYPgKudpwzsUfl/A+5COI3NlNFEsRY6AGjByLMAe Fw5YnKF+o1APq2RBJ0qx0QGA70WAiwc7GJC8j2cXewDc1w6NVmb1LIgO2bckpyWoUzi+9L6/jeqaN gNB7U9Zw==; Received: from [58.29.143.236] (helo=[192.168.1.6]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1tI7lA-00FMrH-A5; Mon, 02 Dec 2024 15:50:48 +0100 Message-ID: <55d10cfc-fed7-489f-94e8-50a7568f5341@igalia.com> Date: Mon, 2 Dec 2024 23:50:40 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/5] sched_ext: Manage the validity of scx_rq_clock To: Peter Zijlstra Cc: tj@kernel.org, void@manifault.com, mingo@redhat.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org References: <20241202043849.1465664-1-changwoo@igalia.com> <20241202043849.1465664-3-changwoo@igalia.com> <20241202095847.GK24400@noisy.programming.kicks-ass.net> From: Changwoo Min Content-Language: en-US, ko-KR, en-US-large, ko In-Reply-To: <20241202095847.GK24400@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hello Peter, On 24. 12. 2. 18:58, Peter Zijlstra wrote: > On Mon, Dec 02, 2024 at 01:38:46PM +0900, Changwoo Min wrote: >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 95e40895a519..ab8015c8cab4 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -789,6 +789,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) >> void update_rq_clock(struct rq *rq) >> { >> s64 delta; >> + u64 clock; >> >> lockdep_assert_rq_held(rq); >> >> @@ -800,11 +801,14 @@ void update_rq_clock(struct rq *rq) >> SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); >> rq->clock_update_flags |= RQCF_UPDATED; >> #endif >> + clock = sched_clock_cpu(cpu_of(rq)); >> + scx_rq_clock_update(rq, clock); > > This adds a write to a second cacheline for *everyone* always. > > Please don't do that. > Thank you for the suggestion! I will update the flags only when the scx is enabled by checking it inside the scx_rq_clock_update() and scx_rq_clock_stale() functions. Regards, Changwoo Min