Bug 46001

Summary: /proc/cpuinfo displays wrong core/siblings count for Intel Atom N270 CPU
Product: Platform Specific/Hardware Reporter: Evangelos Foutras (evangelos)
Component: i386Assignee: platform_i386
Status: NEW ---    
Severity: normal CC: a.p.zijlstra, alan, arthur.titeica, geralt
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 3.5, 3.5.1, 3.7.2, 3.9 Subsystem:
Regression: Yes Bisected commit-id:
Attachments: Diff of /proc/cpuinfo between Linux 3.4.8 and Linux 3.5.1

Description Evangelos Foutras 2012-08-15 05:12:59 UTC
/proc/cpuinfo on Linux 3.5 (and Linux 3.5.1) contains different values for cpu0's "siblings" and cpu1's "siblings" and "cpu cores", compared to the values seen on Linux 3.4.8 (and previous versions).

I came across a relevant-looking fix [1] but it's already included in Linux 3.5.x.

The CPU is an Intel Atom N270 [2] (1 core with Hyper-Threading).

[1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=ceb1cbac8eda66cf0f889def226b4e82f8ff857b
[2] http://ark.intel.com/products/36331/Intel-Atom-Processor-N270-%28512K-Cache-1_60-GHz-533-MHz-FSB%29
Comment 1 Evangelos Foutras 2012-08-15 05:41:09 UTC
Created attachment 77751 [details]
Diff of /proc/cpuinfo between Linux 3.4.8 and Linux 3.5.1
Comment 2 Alfredo Amatriain 2012-09-22 09:28:52 UTC
I'm experiencing the same bug with linux 3.5.3

Originally reported in the Arch bugtracker: