Re: RDTSCP from dlang
On Wednesday, 31 August 2016 at 08:23:57 UTC, Basile B. wrote: By the way maybe someone could post an ER in bugzilla to get RDTSCP available in iasm w/o using the byte code trick. Someone beat me to it, but see here: https://issues.dlang.org/show_bug.cgi?id=16449
Re: RDTSCP from dlang
On Wednesday, 31 August 2016 at 07:34:14 UTC, kookman wrote: On Tuesday, 30 August 2016 at 09:04:41 UTC, Basile B. wrote: Indeed, I want to use rdtscp to get access to the core ID it makes available (to at least know when tsc is from different cores/packages). I guess in the meantime I can use Rikki's solution. Sorry [...] Never mind, I know Rikki's solution is better but since I've read a bit of doc and found this alternative I've just posted the alternative. By the way maybe someone could post an ER in bugzilla to get RDTSCP available in iasm w/o using the byte code trick.
Re: RDTSCP from dlang
On 31/08/2016 7:49 PM, kookman wrote: On Wednesday, 31 August 2016 at 07:36:16 UTC, rikki cattermole wrote: http://dlang.org/spec/abi.html#register_conventions That link talks about for functions defined extern(C) and extern(D), and gives specific info for win32. I'm using linux x86_64, does that mean I can assume standard x86_64 ABI? ie even if the function is not extern? That link describes extern(D) for x86(_64) for all platforms. Keep in mind if a function body does not have an extern(X) supplied, the default is extern(D). C is listed there as we have first class C interaction via extern(C). The listing of DLL's on that page really should be changed to dynamic libraries. Since that covers linuxes.
Re: RDTSCP from dlang
On Wednesday, 31 August 2016 at 07:36:16 UTC, rikki cattermole wrote: http://dlang.org/spec/abi.html#register_conventions That link talks about for functions defined extern(C) and extern(D), and gives specific info for win32. I'm using linux x86_64, does that mean I can assume standard x86_64 ABI? ie even if the function is not extern?
Re: RDTSCP from dlang
On 31/08/2016 7:34 PM, kookman wrote:
On Tuesday, 30 August 2016 at 09:04:41 UTC, Basile B. wrote:
ALternatively to Rikki K's solution, you can do this to mimic the
rdtscp behavior:
asm
{
cpuid;
rdtsc;
// store time in locals
}
// bench
{
rdtsc;
// store time in locals
}
// compute delta
explanations here:
-
http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ia-32-ia-64-benchmark-code-execution-paper.pdf
- http://stackoverflow.com/a/14214220
But according to the first link, this solution, while better than
rdtsc alone, is not as good as rdtscp.
Indeed, I want to use rdtscp to get access to the core ID it makes
available (to at least know when tsc is from different cores/packages).
I guess in the meantime I can use Rikki's solution.
Sorry I'm a DMD asm newbie: DO i need to worry about which registers I
clobber here? I couldn't find any info about this on the Inline Assembly
doco page on dlang.org.
http://dlang.org/spec/abi.html#register_conventions
Re: RDTSCP from dlang
On Tuesday, 30 August 2016 at 09:04:41 UTC, Basile B. wrote:
ALternatively to Rikki K's solution, you can do this to mimic
the rdtscp behavior:
asm
{
cpuid;
rdtsc;
// store time in locals
}
// bench
{
rdtsc;
// store time in locals
}
// compute delta
explanations here:
-
http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ia-32-ia-64-benchmark-code-execution-paper.pdf
- http://stackoverflow.com/a/14214220
But according to the first link, this solution, while better
than rdtsc alone, is not as good as rdtscp.
Indeed, I want to use rdtscp to get access to the core ID it
makes available (to at least know when tsc is from different
cores/packages). I guess in the meantime I can use Rikki's
solution.
Sorry I'm a DMD asm newbie: DO i need to worry about which
registers I clobber here? I couldn't find any info about this on
the Inline Assembly doco page on dlang.org.
Re: RDTSCP from dlang
On Tuesday, 30 August 2016 at 02:04:55 UTC, kookman wrote:
I need to access the x86_64 RDTSCP assembly instruction from D.
I found this for C++:
http://stackoverflow.com/questions/14783782/which-inline-assembly-code-is-correct-for-rdtscp
Does anyone here know how (if?) I can do this from D?
ALternatively to Rikki K's solution, you can do this to mimic the
rdtscp behavior:
asm
{
cpuid;
rdtsc;
// store time in locals
}
// bench
{
rdtsc;
// store time in locals
}
// compute delta
explanations here:
-
http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ia-32-ia-64-benchmark-code-execution-paper.pdf
- http://stackoverflow.com/a/14214220
But according to the first link, this solution, while better than
rdtsc alone, is not as good as rdtscp.
Re: RDTSCP from dlang
On 30/08/2016 2:04 PM, kookman wrote:
I need to access the x86_64 RDTSCP assembly instruction from D.
I found this for C++:
http://stackoverflow.com/questions/14783782/which-inline-assembly-code-is-correct-for-rdtscp
Does anyone here know how (if?) I can do this from D?
It appears dmd's inline assembler does not support it.
So a workaround:
asm {
// rdtscp
db 0x0F;
db 0x01;
db 0xF9;
}
http://dlang.org/spec/iasm.html
RDTSCP from dlang
I need to access the x86_64 RDTSCP assembly instruction from D. I found this for C++: http://stackoverflow.com/questions/14783782/which-inline-assembly-code-is-correct-for-rdtscp Does anyone here know how (if?) I can do this from D?
