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Fri, 22 Jul 2022 12:08:13 +0000 (GMT) Received: from [9.171.62.39] (unknown [9.171.62.39]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 22 Jul 2022 12:08:12 +0000 (GMT) Message-ID: <15df7e57-0126-850d-4ab6-309ec03a2130@linux.ibm.com> Date: Fri, 22 Jul 2022 14:08:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH v8 08/12] s390x/cpu_topology: implementing numa for the s390x topology Content-Language: en-US To: Pierre Morel , qemu-s390x@nongnu.org Cc: qemu-devel@nongnu.org, borntraeger@de.ibm.com, pasic@linux.ibm.com, richard.henderson@linaro.org, david@redhat.com, thuth@redhat.com, cohuck@redhat.com, mst@redhat.com, pbonzini@redhat.com, kvm@vger.kernel.org, ehabkost@redhat.com, marcel.apfelbaum@gmail.com, eblake@redhat.com, armbru@redhat.com, seiden@linux.ibm.com, nrb@linux.ibm.com, frankja@linux.ibm.com References: <20220620140352.39398-1-pmorel@linux.ibm.com> <20220620140352.39398-9-pmorel@linux.ibm.com> <3a821cd1-b8a0-e737-5279-8ef55e58a77f@linux.ibm.com> <14afa5dc-80de-c5a2-b57d-867c692b29cf@linux.ibm.com> <3b2f62a7-b526-adfd-e791-f2bc2cae3ccf@linux.ibm.com> <4d0d25e9-fedf-728c-12e9-70e4dc04d6b7@linux.ibm.com> <2c0b3926-482a-9c3f-1937-1be672ba7aeb@linux.ibm.com> From: Janis Schoetterl-Glausch In-Reply-To: <2c0b3926-482a-9c3f-1937-1be672ba7aeb@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: M8BF2Z0EibtSmByiGT6876XoGTwnOVFk X-Proofpoint-ORIG-GUID: XFyA818wX0HDDHJQTd8cuw_1MaRqIzfR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-22_03,2022-07-21_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 clxscore=1015 mlxlogscore=999 adultscore=0 impostorscore=0 mlxscore=0 spamscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2206140000 definitions=main-2207220051 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 7/21/22 13:41, Pierre Morel wrote: > > > On 7/21/22 10:16, Janis Schoetterl-Glausch wrote: >> On 7/21/22 09:58, Pierre Morel wrote: >>> >>> > > ...snip... > >>> >>> You are right, numa is redundant for us as we specify the topology using the core-id. >>> The roadmap I would like to discuss is using a new: >>> >>> (qemu) cpu_move src dst >>> >>> where src is the current core-id and dst is the destination core-id. >>> >>> I am aware that there are deep implication on current cpu code but I do not think it is not possible. >>> If it is unpossible then we would need a new argument to the device_add for cpu to define the "effective_core_id" >>> But we will still need the new hmp command to update the topology. Why the requirement for a hmp command specifically? Would qom-set on a cpu property work? >>> >> I don't think core-id is the right one, that's the guest visible CPU address, isn't it? > > Yes, the topology is the one seen by the guest. > >> Although it seems badly named then, since multiple threads are part of the same core (ok, we don't support threads). > > I guess that threads will always move with the core or... we do not support threads. > >> Instead socket-id, book-id could be changed dynamically instead of being computed from the core-id. >> > > What becomes of the core-id ? It would stay the same. It has to, right? Can't change the address as reported by STAP. I would just be completely independent of the other ids.