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Tue, 3 Aug 2021 08:26:49 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4FF8FA406F; Tue, 3 Aug 2021 08:26:49 +0000 (GMT) Received: from oc3016276355.ibm.com (unknown [9.145.75.95]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 3 Aug 2021 08:26:49 +0000 (GMT) From: Pierre Morel To: kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, cohuck@redhat.com, david@redhat.com, thuth@redhat.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, pmorel@linux.ibm.com Subject: [PATCH v3 3/3] s390x: optimization of the check for CPU topology change Date: Tue, 3 Aug 2021 10:26:46 +0200 Message-Id: <1627979206-32663-4-git-send-email-pmorel@linux.ibm.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1627979206-32663-1-git-send-email-pmorel@linux.ibm.com> References: <1627979206-32663-1-git-send-email-pmorel@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 1PYLi39yGSt-JEAcbOEjMNil9JiYrdcm X-Proofpoint-ORIG-GUID: JAk0DWKu_RPKFoLoRExq4pCpq571bs7C X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-03_02:2021-08-02,2021-08-03 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 mlxscore=0 clxscore=1015 impostorscore=0 spamscore=0 mlxlogscore=999 malwarescore=0 bulkscore=0 priorityscore=1501 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108030055 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now that the PTF instruction is interpreted by the SIE we can optimize the arch_update_cpu_topology callback to check if there is a real need to update the topology by using the PTF instruction. Signed-off-by: Pierre Morel --- arch/s390/kernel/topology.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c index 26aa2614ee35..741cb447e78e 100644 --- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -322,6 +322,9 @@ int arch_update_cpu_topology(void) struct device *dev; int cpu, rc; + if (!ptf(PTF_CHECK)) + return 0; + rc = __arch_update_cpu_topology(); on_each_cpu(__arch_update_dedicated_flag, NULL, 0); for_each_online_cpu(cpu) { -- 2.25.1