Messages in this thread | | | Date | Sun, 11 Jan 2004 14:28:29 -0500 | From | "Mark W. Alexander" <> | Subject | 2.6.0->2.6.1 /proc/cpuinfo behavior change |
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The behavior of /proc/cpuinfo on cpu frequency scaling has changed between 2.6.0 and 2.6.1(-mm2). On 2.6.0, /proc/cpuinfo reports the cpu MHz as set by scaling_setspeed, with bogo-mips numbers along traditional values.
On 2.6.1-mm2, /proc/cpuinfo _always_ reports cpu MHz == cpuinfo_max_freq, with bogo-mips values closer to the setting of scaling_setspeed.
In both cases, /proc/stat information appears appropriate to the actual speed. (At least, AFAICT, that's where gKrellm get's it's info and it seems to report correctly.)
I didn't glean anything from the changelogs that explains this behavior. Is it a bug or a feature?
Example output: ########################### 2.6.0 ###################### bash-2.05b# uname -r 2.6.0-ze4400-3 bash-2.05b# echo 1800000 >/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed bash-2.05b# cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 8 model name : mobile AMD Athlon(tm) XP2200+ stepping : 1 cpu MHz : 1788.655 cache size : 256 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mp mmxext 3dnowext 3dnow bogomips : 3538.94
bash-2.05b# echo 532000 >/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed bash-2.05b# cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 8 model name : mobile AMD Athlon(tm) XP2200+ stepping : 1 cpu MHz : 529.971 cache size : 256 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mp mmxext 3dnowext 3dnow bogomips : 1048.57
########################### 2.6.1-mm2 ###################### bash-2.05b# uname -r 2.6.1-mm2-ze4400-1 bash-2.05b# echo 1800000 >/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed bash-2.05b# cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 8 model name : mobile AMD Athlon(tm) XP2200+ stepping : 1 cpu MHz : 1789.000 cache size : 256 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mp mmxext 3dnowext 3dnow bogomips : 1777.66
bash-2.05b# echo 532000 >/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed bash-2.05b# cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 8 model name : mobile AMD Athlon(tm) XP2200+ stepping : 1 cpu MHz : 1789.000 cache size : 256 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mp mmxext 3dnowext 3dnow bogomips : 526.71 -- Mark W. Alexander slash@dotnetslash.net - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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