Summary list of ARs from this meeting: AR for Mark: Run the new script on ppc64 and possibly ia64 architectures. AR for Martine: Forward patches to Natalie on returning a CPU to SAL for ia64 architecture. ################################# Attendees: George Mann, BULL Joel Schopp, IBM Renier Morales, IBM Mary Meredith, OSDL Mark Wong, OSDL Natalie Protasevich, Unisys Martine Silbermann, HP * Memory hotplug testing. The problem that Mark was seeing at boot time was due to memory getting corrupted. The memory initialization code was using an optimization that assumed that mem_maps were aligned on MAX_ORDER boundaries and resulted in the possible modification/overwritting of memory outside the mem_maps. The optimization patch was removed from the tree. Mark also wrote a new script to try to offline all the CPUs in one system but hasn't been able to test it. AR for Mark: Run the new script on ppc64 and possibly ia64 architectures. Natalie posted her patch and got some feedback from Ashok and Joel. She's currently implementing the changes following their comments and suggestions. Also Li Shaohua has submitted a patch for CPU hotplug on i386 that seems to complement Natalie's in the sense that he concentrated his efforts in different part of the code but a merge between the patches will be needed. Natalie mentionned that she's currently trying to understand how to best acquire and release the CPU from SAL. AR for Martine: Forward patches to Natalie on returning a CPU to SAL for ia64 architecture. * Use Cases We discussed the possible candidates for use cases for Hotplug. The top 3 candidates were: 1. Reliability, avoiding down time by replacing components that show signs of possible failure. 2. Dynamic System Partitioning, including Instant Capacity on Demand 3. Virtualization - Logical add and remove of resources from a virtual machine. We talked about the format and content of a use case, OSDL is currently developing a template for use cases. Their template will be based on the template originally proposed by Allen Holub http://www-106.ibm.com/developerworks/library/co-design5.html#1 Mary suggested to add another category to the ones listed in this template for "environment", such as what type of system(s) will this run on, 1 big server? in a cluster? etc... For an example of use cases, we can look at the one on PSDN (Persistent Storage Device Naming) http://www.developer.osdl.org/maryedie/STORAGE_NETWORKING/PSDN/PSDN_use_ case.txt Also Chris Wright paper on "Virtualization Techniques in Linux" presented at OLS last year could also be used as a starting point for the use case on Virtualization. http://www.finux.org/Reprints/Reprint-Wright-OLS2004.pdf We discussed the ways hotplug can impact virtualization; performance came up as an important issue. We also discussed the fact that we should separate the 2 cases where Linux is the host and Linux is the guest. CGL is writing a bunch of use cases and some might be relevant to hotplug such as "Diagnostic monitoring framework" and "CPU diagnostics" which are dependencies on the "Reliability" use case. Mary might have a volunteer to start writing the use case on Dynamic Partitioning, he has a lot of experience with hw on demand and dynamic hw partitioning. George offered to help as a reviewer on the Virtualization use case. Next meeting is scheduled for April 26th at 11:00am -12:00pm PST, 2:00pm - 3:00pm EST Thanks for your participation. Martine J. Silbermann
