Messages in this thread | | | Subject | Re: [RFC PATCH] arm64: topology: Map PPTT node offset to logic physical package id | From | Sudeep Holla <> | Date | Thu, 28 Jun 2018 13:12:18 +0100 |
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On 28/06/18 12:57, Andrew Jones wrote: > On Thu, Jun 28, 2018 at 10:38:24AM +0100, Sudeep Holla wrote: >> Hi Shunyong, >> >> On 28/06/18 10:18, Shunyong Yang wrote: >>> As PPTT spec doesn't define the physical package id, >>> find_acpi_cpu_topology_package() will return offset of the node with >>> Physical package field set when querying physical package id. So, it >>> returns 162(0xA2) in following example. >>> >>> [0A2h 0162 1] Subtable Type : 00 [Processor Hierarchy >>> Node] >>> [0A3h 0163 1] Length : 1C >>> [0A4h 0164 2] Reserved : 0000 >>> [0A6h 0166 4] Flags (decoded below) : 00000003 >>> Physical package : 1 >>> ACPI Processor ID valid : 1 >>> [0AAh 0170 4] Parent : 00000000 >>> [0AEh 0174 4] ACPI Processor ID : 00001000 >>> [0B2h 0178 4] Private Resource Number : 00000002 >>> [0B6h 0182 4] Private Resource : 0000006C >>> [0BAh 0186 4] Private Resource : 00000084 >>> >>> So, when "cat physical_package" in /sys/devices/system/cpu/cpu0/topology/, >>> it will output 162(0xA2). And if some items are added before the node >>> above, the output will change to other value. >>> >>> This patch maps the node offset to a logic package id. It maps the first >>> node offset to 0, the second to 1, and so on. >>> >>> Then, it will not output a big value, such as 162 above. And it will >>> not change when some nodes(Physical package not set) are added. >>> >>> And as long as the nodes with Physical package field set in PPTT keeps >>> the real hardware order, the logic id can map to hardware package id to >>> some extent. >>> >>> Hope to get feedback from you. >> >> Thanks for the patch, but Andrew Jones has also posted a patch[1] which >> I had a look but was not sure what is the best approach to fix it yet. >> I will think about it and respond to that. >> > > I'll send a v1 yet today. The RFC version was actually OK, as the concern > with ACPI nodes not being in the expected order wasn't actually a problem. > The thread-id or core-id would only be reset to zero when a yet to be > remapped core-id (and all its peers) was found when iterating the PEs. > Since all peers were handled at the same time, the counter reset was > correct, even when the ACPI nodes were out-of-order. The code didn't make > that very obvious, though, and there was some room for other cleanups, > so I've reworked it. Once I run it through a couple more rounds of testing > I'll repost. >
OK sure. I liked the approach in Shunyong's patch. I was thinking if we can avoid the list and dynamic allocation on each addition and make it more simpler.
-- Regards, Sudeep
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