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digitalmars.D.bugs - [Issue 4462] New: core.cpuid wrong on Intel machines w/ multiple physical CPUs

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4462

           Summary: core.cpuid wrong on Intel machines w/ multiple
                    physical CPUs
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: druntime
        AssignedTo: sean invisibleduck.org
        ReportedBy: dsimcha yahoo.com


--- Comment #0 from David Simcha <dsimcha yahoo.com> 2010-07-14 12:33:35 PDT ---
Test Program:

import core.cpuid, std.stdio;

void main() {
    writeln("Cores:  ", coresPerCPU, "  Threads:  ", threadsPerCPU);
}

This prints the following on the machine in question:

Cores:  1  Threads:  2 

cat /proc/cpuinfo on same machine:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7321.79
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 4
siblings        : 2
core id         : 4
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7314.82
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 2
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 3
siblings        : 2
core id         : 3
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7315.15
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 3
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 7
siblings        : 2
core id         : 7
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7315.01
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 4
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7315.01
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 5
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 4
siblings        : 2
core id         : 4
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7315.07
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 6
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 3
siblings        : 2
core id         : 3
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7315.13
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 7
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                Intel(R) Xeon(TM) MP CPU 3.66GHz
stepping        : 1
cpu MHz         : 3657.825
cache size      : 1024 KB
physical id     : 7
siblings        : 2
core id         : 7
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm pni monitor
ds_cpl est tm2 cid cx16 xtpr
bogomips        : 7315.03
clflush size    : 64
cache_alignment : 128
address sizes   : 40 bits physical, 48 bits virtual
power management:

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4462


Russel Winder <russel russel.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |russel russel.org.uk


--- Comment #1 from Russel Winder <russel russel.org.uk> 2011-02-27 05:51:06
PST ---
OK this bug has been open for 7 months and no action.  Surely this is no an
urgent blocking bug.

Note also Issue 5612 which shows that the code is broken with 64-bit processors
as well as multiple processors.

Can cpuid.d be separated out so that we can work on it?

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug yahoo.com.au


--- Comment #2 from Don <clugdbug yahoo.com.au> 2011-02-27 06:52:01 PST ---
(In reply to comment #0)
 Test Program:
 
 import core.cpuid, std.stdio;
 
 void main() {
     writeln("Cores:  ", coresPerCPU, "  Threads:  ", threadsPerCPU);
 }
 
 This prints the following on the machine in question:
 
 Cores:  1  Threads:  2 
 
 cat /proc/cpuinfo on same machine:
 
 processor       : 0
 cpu cores       : 1
 processor       : 1
 cpu cores       : 1
 processor       : 2
 cpu cores       : 1
That isn't enough information to demonstrate a bug. proc/cpuinfo reports 8 processors, each with one core each. Thus, I would expect coresPerCPU to be 1. Can you please give a valid test case? (Seems as though you'll need to display the number of processors). -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
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--- Comment #3 from Don <clugdbug yahoo.com.au> 2011-02-27 13:59:51 PST ---
To clarify: core.cpuid does NOT provide the number of CPUs in the system.
Hence, it does not give the total number of available cores.

core.cpuid gives the number of cores in each CPU, and the number of
hyperthreads in each core. This means that it has sufficient information to do
cache blocking correctly.

The total number of physical CPUs is required only when distributing work
between cores (you never need to know it when scheduling within a core).
Determining this is OS-dependent, and is actually pretty useless unless you
also have some way of controlling the processor affinity, as well. Although
this is stuff we will definitely need, it's quite a different situation from
bugs in the existing code.

Are there any cases where the reported values are actually wrong? Or is this a
feature request for the number of physical CPUs?

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David Simcha <dsimcha yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|core.cpuid wrong on Intel   |core.cpuid:  Need way to
                   |machines w/ multiple        |get total number of
                   |physical CPUs               |sockets/physical CPUs


--- Comment #4 from David Simcha <dsimcha yahoo.com> 2011-02-27 14:15:37 PST ---
(In reply to comment #3)
 To clarify: core.cpuid does NOT provide the number of CPUs in the system.
 Hence, it does not give the total number of available cores.
 ...
 Are there any cases where the reported values are actually wrong? Or is this a
 feature request for the number of physical CPUs?
This is definitely an enhancement request then. As far as I can tell, the cores per CPU stuff is actually right (I think). It's just that I vaguely remember you stating the opposite at one point, that coresPerCPU actually is a misnomer and gives the total number of cores across all CPUs. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
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David Simcha <dsimcha yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement


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David Simcha <dsimcha yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


--- Comment #5 from David Simcha <dsimcha yahoo.com> 2011-08-12 20:47:06 PDT ---
std.parallelism.totalCPUs addresses this.

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