linux-kernel - [PATCH 0/2] turbostat, support CPU0 hotplug

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Date:	Fri, 22 May 2015 08:01:01 -0400
From:	Prarit Bhargava <prarit@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	len.brown@...el.com, andrey.semin@...el.com,
	Prarit Bhargava <prarit@...hat.com>
Subject: [PATCH 0/2] turbostat, support CPU0 hotplug

turbostat does not function properly on systems that support CPU0 hotplug.
When running turbostat on these systems the following error is seen.

[root@...el-chiefriver-04 ~]# turbostat ls
turbostat: no /dev/cpu/0/msr
Try "# modprobe msr": No such file or directory

This happens because in many places turbostat hardcodes 0, and calls
to check_dev_msr(), for example, will fail if CPU0 has been removed.

This patchset adds functionality to determine the lowest found cpu on the
system, and to use that value instead of 0.  This patchset also  moves
setup_all_buffers() to the beginning of the turbostat_init() so that
set_base_cpu() can take advantage of topo.max_cpu_num which is set in
setup_all_buffers().

After this change, on a system that has CPU0 removed,

[root@...rit ~]# ./turbostat -d -d ls
turbostat version 4.5 2 Apr, 2015 - Len Brown <lenb@...nel.org>
num_cpus 7 max_cpu_num 7
cpu0 NOT PRESENT
cpu 1 pkg 0 core 0
cpu 2 pkg 0 core 1
cpu 3 pkg 0 core 1
cpu 4 pkg 0 core 2
cpu 5 pkg 0 core 2
cpu 6 pkg 0 core 3
cpu 7 pkg 0 core 3
<snip>
anaconda-ks.cfg  README  turbostat
Core     CPU Avg_MHz   %Busy Bzy_MHz TSC_MHz     SMI  CPU%c1  CPU%c3  CP
   -       -     492   14.20    3462    2634       0   18.90    0.00    
   0       1     353    9.95    3552    2645       0    9.68    0.00    
   1       2     217    7.70    2814    2614       0   64.63    0.00    
   1       3    2006   57.20    3507    2660       0   15.61
   2       4     120    3.37    3570    2649       0   10.95    0.00    
   2       5     155    4.22    3679    2631       0    9.48
   3       6     296    8.38    3530    2620       0   11.07    0.00    
   3       7     296    8.15    3630    2617       0   11.22
0.001160 sec

I have additionally tested various other hotplug configurations to make sure
that turbostat behaves correctly in those situations as well.

Prarit Bhargava (2):
  turbostat, add base_cpu
  turbostat, add set_base_cpu()

 tools/power/x86/turbostat/turbostat.c | 49 +++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 14 deletions(-)

-- 
1.8.3.1

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