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Physical CPU and core detection https://powerdeveloper.org/forums/viewtopic.php?f=60&t=1922 |
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Author: | slim_samu [ Thu Feb 10, 2011 6:12 pm ] |
Post subject: | Physical CPU and core detection |
Hello all, I have what may see a bizarre question. The only ARM hardware I have access to is all single core (and single socket); this includes the Efika MX. Although I've not looked at the kernel sources yet, I'm looking to understand if anybody has seen a /proc/cpuinfo file from an ARM based system equipped with multiple CPUs or CPUs which are multi-core? It's really to determine how to count on such systems the number of cores vs. the number of sockets. |
Author: | ojn [ Thu Feb 10, 2011 11:44 pm ] |
Post subject: | |
There are no multi-socket ARM systems. |
Author: | hrw [ Mon Feb 14, 2011 10:41 am ] |
Post subject: | |
root@omap4430-panda:~# cat /proc/cpuinfo Processor : ARMv7 Processor rev 2 (v7l) processor : 0 BogoMIPS : 2013.49 processor : 1 BogoMIPS : 1996.68 Features : swp half thumb fastmult vfp edsp thumbee neon vfpv3 CPU implementer : 0x41 CPU architecture: 7 CPU variant : 0x1 CPU part : 0xc09 CPU revision : 2 Hardware : OMAP4430 Panda Board Revision : 0020 Serial : 0000000000000000 |
Author: | steev [ Mon Feb 14, 2011 12:01 pm ] |
Post subject: | |
That is dual core, not dual socket isn't it hrw? |
Author: | hrw [ Tue Feb 15, 2011 4:54 am ] |
Post subject: | |
This is from dualcore ARM system. |
Author: | gbyers [ Thu Feb 17, 2011 6:47 pm ] |
Post subject: | |
On at least some dual-core Tegra 2 systems (and on at least some Linux flavors), the second core gets shutdown when (something, somewhere) decides that doing so would save power (and that the load on the system has been light enough to justify that.) When the second core is offline, there's no entry for it in /proc/cpuinfo (so parsing that file isn't a reliable way of detecting that one's on a multicore system.) sysconf(_SC_PROCESSORS_CONF) returns the number of configured cores and is generally an upper bound on the number of cores that can be online. |
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