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Fri, 28 May 2021 07:53:02 +0000 (GMT) Received: from localhost.localdomain (unknown [9.199.32.139]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTP; Fri, 28 May 2021 07:53:02 +0000 (GMT) Subject: Re: [RFC v2 4/4] powerpc/papr_scm: Add cpu hotplug support for nvdimm pmu device To: Peter Zijlstra Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, maddy@linux.vnet.ibm.com, santosh@fossix.org, aneesh.kumar@linux.ibm.com, vaibhav@linux.ibm.com, dan.j.williams@intel.com, ira.weiny@intel.com, atrajeev@linux.vnet.ibm.com, tglx@linutronix.de, rnsastry@linux.ibm.com References: <20210525132216.1239259-1-kjain@linux.ibm.com> <20210525132216.1239259-5-kjain@linux.ibm.com> From: kajoljain Message-ID: Date: Fri, 28 May 2021 13:23:00 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 0MXISzsXWyIm5rY7s9lJENnNmh6HXMYm X-Proofpoint-ORIG-GUID: 0MXISzsXWyIm5rY7s9lJENnNmh6HXMYm X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-05-28_03:2021-05-27,2021-05-28 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 mlxlogscore=959 malwarescore=0 clxscore=1015 impostorscore=0 mlxscore=0 suspectscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105280049 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/26/21 2:02 PM, Peter Zijlstra wrote: > On Wed, May 26, 2021 at 12:56:58PM +0530, kajoljain wrote: >> On 5/25/21 7:46 PM, Peter Zijlstra wrote: >>> On Tue, May 25, 2021 at 06:52:16PM +0530, Kajol Jain wrote: > >>>> It adds cpumask to designate a cpu to make HCALL to >>>> collect the counter data for the nvdimm device and >>>> update ABI documentation accordingly. >>>> >>>> Result in power9 lpar system: >>>> command:# cat /sys/devices/nmem0/cpumask >>>> 0 >>> >>> Is this specific to the papr thing, or should this be in generic nvdimm >>> code? >> >> This code is not specific to papr device and we can move it to >> generic nvdimm interface. But do we need to add some checks on whether >> any arch/platform specific driver want that support or we can assume >> that this will be something needed by all platforms? > > I'm a complete NVDIMM n00b, but to me it would appear they would have to > conform to the normal memory hierarchy and would thus always be > per-node. > > Also, if/when deviation from this rule is observed, we can always > rework/extend this. For now I think it would make sense to have the > per-node ness of the thing expressed in the generic layer. > Hi Peter, Thanks for the suggestion, I will send new RFC patchset with these changes. Thanks, Kajol Jain