Apple Developer Transition Kit

[marcov]

On 64-bit Windows it returns "8", which is my 4 physical core + 4 hyperthreading cores.

[Fred vS]

On 64-bit Windows it returns "8", which is my 4 physical core + 4 hyperthreading cores.

Huh, indeed, on Linux compiling GetCPUCount() with wine fpc.exe and then run the Windows binary with
wine gives "4" as result!

But same code compiled for Linux and run the Linux binary gives "1" as result.

[EDIT]
And with the Linux command:

Code: Bash  [Select][+][-]

1. $ lscpu

It gives "8" cpu.

[skalogryz]

System.GetCPUCount() always returns "1" on Apple Silicon CPU. It should be 4 or maybe 8 cores.

the function doesn't seem to be implemented for Unix systems.

What does processorCount return?

[skalogryz]

But same code compiled for Linux and run the Linux binary gives "1" as result.

how about this code:

Code: Pascal  [Select][+][-]

1. uses
2.   cthreads;
3.  
4. function get_nprocs_conf: integer; cdecl; external;
5.  
6. function GetCPUCountLinux: Integer;
7. begin
8.   Result := get_nprocs_conf;
9. end;
10.  
11. begin
12.   writeln('proc count: ', GetCPUCountLinux);
13. end.  
14.  

[skalogryz]

another Linux/macOS version:

Code: Pascal  [Select][+][-]

1. {$mode objfpc}{$H+}
2.  
3. uses
4.   ctypes;
5.  
6. const
7.   // the value changes across Unix OS-es
8.   _SC_NPROCESSORS_ONLN           = {$ifdef darwin}58{$endif} // macOS
9.                                    {$else}84{$endif};  // linux
10.  
11. function sysconf(conf: cint): clong; cdecl; external;
12.  
13. function GetCPUCountUnix: Integer;
14. begin
15.   Result := sysconf(_SC_NPROCESSORS_ONLN);
16. end;
17.  
18. begin
19.   writeln('proc count: ', GetCPUCountUnix);
20. end.      
21.  

[Fred vS]

But same code compiled for Linux and run the Linux binary gives "1" as result.

how about this code:

Code: Pascal  [Select][+][-]

1. uses
2.   cthreads;
3.  
4. function get_nprocs_conf: integer; cdecl; external;
5.  
6. function GetCPUCountLinux: Integer;
7. begin
8.   Result := get_nprocs_conf;
9. end;
10.  
11. begin
12.   writeln('proc count: ', GetCPUCountLinux);
13. end.  
14.  

Yep, it works:

Code: Bash  [Select][+][-]

1. ~> ./testcpu
2. proc count: 8

[Fred vS]

another Linux/macOS version:

Code: Pascal  [Select][+][-]

1. {$mode objfpc}{$H+}
2.  
3. uses
4.   ctypes;
5.  
6. const
7.   // the value changes across Unix OS-es
8.   _SC_NPROCESSORS_ONLN           = {$ifdef darwin}58{$endif} // macOS
9.                                    {$else}84{$endif};  // linux
10.  
11. function sysconf(conf: cint): clong; cdecl; external;
12.  
13. function GetCPUCountUnix: Integer;
14. begin
15.   Result := sysconf(_SC_NPROCESSORS_ONLN);
16. end;
17.  
18. begin
19.   writeln('proc count: ', GetCPUCountUnix);
20. end.      
21.  

This one gives at compilation:

Compiling testcpu.pas
Linking testcpu
/usr/bin/ld: testcpu.o: in function `P$TESTCPU_$$_GETCPUCOUNTUNIX$$LONGINT':
testcpu.pas:(.text.n_p$testcpu_$$_getcpucountunix$$longint+0x11): undefined reference to `sysconf'
testcpu.pas(22,5) Error: Error while linking
testcpu.pas(22,5) Fatal: There were 1 errors compiling module, stopping
Fatal: Compilation aborted

[skalogryz]

please add cthreads to the uses clause. This should link the required library

[Fred vS]

please add cthreads to the uses clause. This should link the required library

Ha, ok, now it compiles ok and the result is ok too.

Code: Pascal  [Select][+][-]

1. ~> ./testcpu
2. proc count: 8

[Igor Kokarev]

skalogryz,

Thanks for your reply!

Your code works fine on both Macs - Intel and Apple DTK:

DTK returns "8" cores.

Code: Pascal  [Select][+][-]

1. {$mode objfpc}{$H+}
2.  
3. uses
4.   ctypes, cthreads;
5.  
6. const
7.   // the value changes across Unix OS-es
8.   _SC_NPROCESSORS_ONLN           = {$ifdef darwin}58{$endif} // macOS
9.                                    {$else}84{$endif};  // linux
10.  
11. function sysconf(conf: cint): clong; cdecl; external;
12.  
13. function GetCPUCountUnix: Integer;
14. begin
15.   Result := sysconf(_SC_NPROCESSORS_ONLN);
16. end;
17.  
18. begin
19.   writeln('proc count: ', GetCPUCountUnix);
20. end.

Another variant doesn't link on Apple DTK for aarch64:

Code: Pascal  [Select][+][-]

1. uses
2.   cthreads;
3.  
4. function get_nprocs_conf: integer; cdecl; external;
5.  
6. function GetCPUCountLinux: Integer;
7. begin
8.   Result := get_nprocs_conf;
9. end;
10.  
11. begin
12.   writeln('proc count: ', GetCPUCountLinux);
13. end.  

[marcov]

What value does the number of logical cores _alone_ have? It is only useful if you also have the physical cores. (e.g. if you have 6 real cores + HT, then start 8 threads. But starting twelve is nearly always overkill)

[Igor Kokarev]

Apple DTK has 8 cores (4 high-speed and 4 energy saving).

[skalogryz]

Another variant doesn't link on Apple DTK for aarch64:

it should not link on macOS. get_nprocs_conf() is a Linux specific function.

What about processorCount?

The code might look like thise

Code: Pascal  [Select][+][-]

1. uses
2.   CocoaAll;
3. {$modeswitch objectiveC2}
4.  
5. begin
6.   writeln('proc count: ', NSProcessInfo processInfo.processorCount);
7. end.  

[marcov]

Apple DTK has 8 cores (4 high-speed and 4 energy saving).

Can they all work in parallel? If not, than that is the a different setup, but the same problem.

IOW what good does the figure "8" for cores if only 4 can work at any one given time?

[Jonas Maebe]

Apple DTK has 8 cores (4 high-speed and 4 energy saving).

Can they all work in parallel?

Yes.