From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 6C2E1215F51 for ; Thu, 9 Jan 2025 10:21:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736418091; cv=none; b=D3c9/Tnlg1bD/qDR81uEv+rD3UZ8NTDoYkAqhhzRJfgqrHKN5sJKqEouwAr+EOHPe9JcfNBLFGxA79A/Cp4dMWtexFEHrXU8kwrVIkpcxk+aoxEkJlTJhEPrh8Xm3AOgx4hdd6ONfdJNjuUsm3kr+yonpHEWiNz+DeYL0chHSB4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736418091; c=relaxed/simple; bh=6p/bJpss8fhTkFECqVzG88q3ux9eaK1OmghJmIxkStM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LTEb177T2g1Te78Se+rydWwFjociH/29CO0Xro3d/d+dcvgywiM7XTsNB2Kh/49LvKl739Xja1r6WxCXQiK0ouWMiK8/09w3eB58d71aF9gpcP0nzy0R2iVfPFNzCOuuX8qoo3C/JbUZsMZjV9GZ9JSXuUa9PYidt46k0Sus5Ew= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=KVso7Z7e; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="KVso7Z7e" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0SDbHEs/3y2wIGwDMXfiKZER4pmxjbope173k0BJs8M=; b=KVso7Z7eVoeyr0BPZe4A0rr0Us d3LzTb8G7lxh0kg+HJJExAU5ux7ZFN4dHCXuzfTXq0fLLb1PdCAJI6eskbqCDZZcJp5NHtFmJAGTA 1Sg4s3TF2ya9ASu6/p5XWtNuNVLiXFIW806SH9cK+i066JOzkJAKnHp6JPfEC2ysvavOayqjE69fH 3aSu0t1/5d13SDY6kTD/ZR0JvmSFX+Gv+Gg+UDPl91oZ1k6KEGxCHtX/nUfHhPYpP/kYpKu3zNcBv xprKZQqsRnvUNR2gudaVXp8Ha0cGmewlWSW4Dhazf54c6Q1Ml8KZ/8OHb/HfvPEJ7YScASFD2axRF YlvDNM4w==; Received: from 77-249-17-89.cable.dynamic.v4.ziggo.nl ([77.249.17.89] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tVpfH-00000009Xsj-1MvI; Thu, 09 Jan 2025 10:21:23 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 6799B30057A; Thu, 9 Jan 2025 11:21:22 +0100 (CET) Date: Thu, 9 Jan 2025 11:21:22 +0100 From: Peter Zijlstra To: I Hsin Cheng Cc: mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] sched/fair: Refactor can_migrate_task() to elimate looping Message-ID: <20250109102122.GQ20870@noisy.programming.kicks-ass.net> References: <20250108172948.452158-1-richard120310@gmail.com> <20250109094627.GP20870@noisy.programming.kicks-ass.net> 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=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Jan 09, 2025 at 06:12:22PM +0800, I Hsin Cheng wrote: > > > Except you cannot put cpumask on-stack... > > Oh I'm sorry, may I ask the reason? is it because cpumask tends to be > very large? Yes, when building with NR_CPUS=8192 (as Distos tend to do) it is 1K of stack space.