From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.113 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793533361; b=DsUCmyxkrqp8CrxiiqDHaTz7RzwROntPTbnuNOIY3ww2PR9Y5hQC3bFcmcokUrsQ2FWG uvxvWJKwIx2no1lwJNZmmIV9N5EP55GjFr3j6qeWvTCS8djC5Zzn4vv67yXW/7vc5lPOb SMq+CB5d3En7uKV0IYJY9/rLc5jAzeoW3qvfYP3o4lcIA6hZbf2cG+r0XHytrnvs2JNEA GX+sEGL/Z59kzkCrcxx5z4XNm+yxFpf7bcekjnit+0okdL1oQ0k+F+MEdNCSWCx1EufNT Uj5ZaeNaaksHL0BcpRAhUCx5aKMr2b9Ms7sd/HwoKG0uvXlvGCHb0CZQcafwVFW29bA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793533361; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-Id: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=UHpXoPugAqHx4I5ouKjWjsQS5zcx6izGx0KtiwpJ9OY=; b=Dow8RRo+1HY0kf8y/cVvX1viTjKtYmXhpzTFvQrs6G500s3oxIhJQjwiasavnJXwLwPD gp0rjDEne8o3AuGa91duNo+MWpKr3EbDx1PcgoCpEJQOLPef25MUBDyJrCMmAQqlXlNNF b24mot4Xh60rRbxWkOJNmVGzM5jYLP9CUmkPeNoljbF6/TS+NQE3yhLsVwgcEWguFAjXS 3Ueid1kYqjed64J6Kv8Pa0UjIB5sR3PO+QVpnLSMJt+twh7ek1sfKT05qXeqZluuLruvt HBI7bT2/8+Kvf9qMfbmbtZsgPOgI0i3J8QATFGd5bWSRIfvzoAlh2s3Y+XClOtPe3ew== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=gbUW66aK; arc=none smtp.remote-ip=95.215.58.113 Received: from mta1.migadu.com (out-113.mta1.migadu.com [95.215.58.113]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CBDD8606A325 for ; Sun, 1 Nov 2026 11:42:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org CBDD8606A325 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=gbUW66aK X-Envelope-To: cgroups@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=k0nX/8o+pq4RV2o6BwBi9o4kCopShjx8ODswENEcNdA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793533357; v=1; x=1794138157; b=gbUW66aKUTC+M9u3y0zzJIahc/zkBQ6RJPGsHNbu8Dxpss2jW85sh0VBALsNC6hCBXCgrNxI 1xDIe2p0EY1gIxfc7Gz2evFvo8g7DD2Fc7UshXL/4QaspVHkiIf3XgCvNOtj1m8sMDKP241iQQ5 mk25/ELdEagOcNLwHrYg2lDg= X-Envelope-To: cgroups@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 292892e7b76a2c6a; Sun, 01 Nov 2026 11:42:37 +0000 X-Mizu-Trace-ID: 292892e7b76a2c6a X-Migadu-Flow: FLOW_OUT From: Ridong Chen To: Waiman Long , Tejun Heo , Johannes Weiner , "Michal Koutn?" Cc: Guopeng Zhang , Ridong Chen , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Ridong , Ridong Chen Subject: [RFC PATCH -v4 01/22] cpuset: add early empty cpumask check in partition_xcpus_add/del Date: Sun, 1 Nov 2026 19:41:45 +0800 Message-Id: <20261101114206.2434398-2-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261101114206.2434398-1-ridong.chen@linux.dev> References: <20261101114206.2434398-1-ridong.chen@linux.dev> X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chen Ridong Add a check for an empty cpumask at the start of partition_xcpus_add() and partition_xcpus_del(). This allows the functions to return early, avoiding unnecessary computation when there is no work to be done. With these changes, partition_xcpus_add() and partition_xcpus_del() can be called even if xcpus is empty. The caller no longer needs to check whether xcpus is empty, eliminating many conditional statements. Signed-off-by: Chen Ridong Signed-off-by: Ridong Chen --- kernel/cgroup/cpuset.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 3219f927c35e..72e1df1295e1 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1315,10 +1315,13 @@ static void partition_xcpus_add(int new_prs, struct cpuset *parent, { WARN_ON_ONCE(new_prs < 0); lockdep_assert_held(&callback_lock); + + if (cpumask_empty(xcpus)) + return; + if (!parent) parent = &top_cpuset; - if (parent == &top_cpuset) cpumask_or(subpartitions_cpus, subpartitions_cpus, xcpus); @@ -1342,6 +1345,10 @@ static void partition_xcpus_del(int old_prs, struct cpuset *parent, { WARN_ON_ONCE(old_prs < 0); lockdep_assert_held(&callback_lock); + + if (cpumask_empty(xcpus)) + return; + if (!parent) parent = &top_cpuset; -- 2.34.1