Messages in this thread | | | Date | Tue, 24 Nov 2015 15:13:28 +0800 | From | Tang Chen <> | Subject | Re: [PATCH v3 0/5] Make cpuid <-> nodeid mapping persistent. |
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On 11/24/2015 06:04 AM, Tejun Heo wrote: > Hello, > > On Thu, Nov 19, 2015 at 12:22:10PM +0800, Tang Chen wrote: >> [Solution] >> >> There are four mappings in the kernel: >> 1. nodeid (logical node id) <-> pxm >> 2. apicid (physical cpu id) <-> nodeid >> 3. cpuid (logical cpu id) <-> apicid >> 4. cpuid (logical cpu id) <-> nodeid >> >> 1. pxm (proximity domain) is provided by ACPI firmware in SRAT, and nodeid <-> pxm >> mapping is setup at boot time. This mapping is persistent, won't change. >> >> 2. apicid <-> nodeid mapping is setup using info in 1. The mapping is setup at boot >> time and CPU hotadd time, and cleared at CPU hotremove time. This mapping is also >> persistent. >> >> 3. cpuid <-> apicid mapping is setup at boot time and CPU hotadd time. cpuid is >> allocated, lower ids first, and released at CPU hotremove time, reused for other >> hotadded CPUs. So this mapping is not persistent. >> >> 4. cpuid <-> nodeid mapping is also setup at boot time and CPU hotadd time, and >> cleared at CPU hotremove time. As a result of 3, this mapping is not persistent. >> >> To fix this problem, we establish cpuid <-> nodeid mapping for all the possible >> cpus at boot time, and make it persistent. And according to init_cpu_to_node(), >> cpuid <-> nodeid mapping is based on apicid <-> nodeid mapping and cpuid <-> apicid >> mapping. So the key point is obtaining all cpus' apicid. > I don't know much about acpi so can't actually review the patches but > the overall approach looks good to me.
Thank you, TJ. Will test it recently.
> > Thanks. >
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