Feature #8809
closedProcess.clock_getres
Description
How about Process.clock_getres method?
POSIX defines clock_getres function to provide resolution information
of clocks.
I made a pacth to invoke clock_getres function.
Process.clock_getres(Process::CLOCK_MONOTONIC) #=> 1.0e-09
Process.clock_getres(Process::CLOCK_MONOTONIC_COARSE) #=> 0.00400025
The result means that the resolution of CLOCK_MONOTONIC is 1ns and
the resolution of CLOCK_MONOTONIC_COARSE is 4.00025ms.
Process.clock_getres has optional unit argument as Process.clock_gettime.
Process.clock_getres(Process::CLOCK_MONOTONIC, :nanosecond) #=> 1
Process.clock_getres(Process::CLOCK_MONOTONIC_COARSE, :nanosecond) #=> 4000250
It supports emulated clocks as well.
Process.clock_getres(:SUS_GETTIMEOFDAY_BASED_CLOCK_REALTIME) #=> 1.0000000000000002e-06
Process.clock_getres(:SUS_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID) #=> 1.0000000000000002e-06
The unit argument can be :hertz, which means the reciprocal of the second.
Process.clock_getres(:SUS_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) #=> 1000000.0
Note that
Process.clock_getres(:POSIX_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is the clock ticks per second (CLK_TCK) and
Process.clock_getres(:ISO_C_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is CLOCK_PER_SEC.
I wanted to access them easily to investigate emulated clock behaviors on
various OSes.
Any comments?
Files
Updated by david_macmahon (David MacMahon) about 11 years ago
On Aug 22, 2013, at 7:33 AM, akr (Akira Tanaka) wrote:
I made a pacth to invoke clock_getres function.
Thanks for making a patch! It makes the discussion much less abstract (more real?). I think I will try to follow your example in the future.
Process.clock_getres(Process::CLOCK_MONOTONIC) #=> 1.0e-09
Process.clock_getres(Process::CLOCK_MONOTONIC_COARSE) #=> 0.00400025The result means that the resolution of CLOCK_MONOTONIC is 1ns and
the resolution of CLOCK_MONOTONIC_COARSE is 4.00025ms.
Did you consider having these methods return Rational rather than Float?
Process.clock_getres has optional unit argument as Process.clock_gettime.
Process.clock_getres(Process::CLOCK_MONOTONIC, :nanosecond) #=> 1
Process.clock_getres(Process::CLOCK_MONOTONIC_COARSE, :nanosecond) #=> 4000250It supports emulated clocks as well.
Process.clock_getres(:SUS_GETTIMEOFDAY_BASED_CLOCK_REALTIME) #=> 1.0000000000000002e-06
Process.clock_getres(:SUS_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID) #=> 1.0000000000000002e-06The unit argument can be :hertz, which means the reciprocal of the second.
Process.clock_getres(:SUS_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) #=> 1000000.0
How would you feel about supporting :ns and :hz as equivalents for :nanosecond and :hertz?
Note that
Process.clock_getres(:POSIX_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is the clock ticks per second (CLK_TCK) and
Process.clock_getres(:ISO_C_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is CLOCK_PER_SEC.
I wanted to access them easily to investigate emulated clock behaviors on
various OSes.
Those are some long symbols! Are these intended only for experimental/investigative use?
Any comments?
I appreciate having access to POSIX functionality, so I'm all for this idea!
Thanks,
Dave
Updated by akr (Akira Tanaka) about 11 years ago
2013/8/23 David MacMahon davidm@astro.berkeley.edu:
Process.clock_getres(Process::CLOCK_MONOTONIC) #=> 1.0e-09
Process.clock_getres(Process::CLOCK_MONOTONIC_COARSE) #=> 0.00400025The result means that the resolution of CLOCK_MONOTONIC is 1ns and
the resolution of CLOCK_MONOTONIC_COARSE is 4.00025ms.Did you consider having these methods return Rational rather than Float?
Process.clock_getres can return rational if it supports
:rational_second as a unit.
The current default of unit is :float_second and
I think float is good enough.
Process.clock_getres(:SUS_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) #=> 1000000.0
How would you feel about supporting :ns and :hz as equivalents for :nanosecond and :hertz?
It is difficult to support :microsecond in that style
because the SI prefix, Greek m, is not representable in ASCII.
Someone may argue :hz should be :Hz.
I feel :float_s is bit curious.
So it is difficult to adopt :ns style as canonical style of unit.
I think several aliases are possible but
I'd like to concentrate to main feature.
The discussion for what aliases should be added or not can be diverge.
Note that
Process.clock_getres(:POSIX_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is the clock ticks per second (CLK_TCK) and
Process.clock_getres(:ISO_C_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is CLOCK_PER_SEC.
I wanted to access them easily to investigate emulated clock behaviors on
various OSes.Those are some long symbols! Are these intended only for experimental/investigative use?
I choose the long symbols that is longer than Process::CLOCK_PROCESS_CPUTIME_ID.
Basically users should use Process::CLOCK_PROCESS_CPUTIME_ID if no reason.
Tanaka Akira
Updated by david_macmahon (David MacMahon) about 11 years ago
On Aug 22, 2013, at 3:37 PM, Tanaka Akira wrote:
Process.clock_getres can return rational if it supports
:rational_second as a unit.The current default of unit is :float_second and
I think float is good enough.
Agreed. Plus, if someone really wants, they can request nanosecond precision, which is all that clock_getres supports (at least on Linux).
Process.clock_getres(:SUS_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) #=> 1000000.0
How would you feel about supporting :ns and :hz as equivalents for :nanosecond and :hertz?
It is difficult to support :microsecond in that style
because the SI prefix, Greek m, is not representable in ASCII.
I know it's not SI, but I often use ASCII "u" for Greek m ("µ"), so :microsecond would be aliased by :us.
Someone may argue :hz should be :Hz.
No doubt! :-)
I feel :float_s is bit curious.
How about separating the type and the resolution into two different parameters?
Process.clock_getres(Process::CLOCK_MONOTONIC, :float, :second)
...or...
Process.clock_getres(Process::CLOCK_MONOTONIC, Float, :second)
So it is difficult to adopt :ns style as canonical style of unit.
I think several aliases are possible but
I'd like to concentrate to main feature.
The discussion for what aliases should be added or not can be diverge.
Agreed. I think the main feature is great!
Note that
Process.clock_getres(:POSIX_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is the clock ticks per second (CLK_TCK) and
Process.clock_getres(:ISO_C_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) is CLOCK_PER_SEC.
I wanted to access them easily to investigate emulated clock behaviors on
various OSes.Those are some long symbols! Are these intended only for experimental/investigative use?
I choose the long symbols that is longer than Process::CLOCK_PROCESS_CPUTIME_ID.
Basically users should use Process::CLOCK_PROCESS_CPUTIME_ID if no reason.
Sounds good.
Dave
Updated by akr (Akira Tanaka) about 11 years ago
david_macmahon (David MacMahon) wrote:
I know it's not SI, but I often use ASCII "u" for Greek m ("µ"), so :microsecond would be aliased by :us.
It may be possible.
I found ISO 2955.
ISO 2955: Information processing - Representation units in Systems with limited Character sets
I feel :float_s is bit curious.
How about separating the type and the resolution into two different parameters?
Process.clock_getres(Process::CLOCK_MONOTONIC, :float, :second)
...or...
Process.clock_getres(Process::CLOCK_MONOTONIC, Float, :second)
I think most useful combinations are follows.
- float second
- integer nanosecond (clock_gettime/clock_getres native format)
The current design makes us possible to specify
former as no unit argument and
later as :nanosecond.
Your design force us longer description for integer nanosecond.
Updated by akr (Akira Tanaka) about 11 years ago
- File clock_getres-2.patch clock_getres-2.patch added
I updated the patch.
Updated by akr (Akira Tanaka) about 11 years ago
- File clock_getres-3.patch clock_getres-3.patch added
I updated the patch again.
Updated by akr (Akira Tanaka) about 11 years ago
- Status changed from Open to Closed
- % Done changed from 0 to 100
This issue was solved with changeset r42744.
Akira, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.
-
process.c (rb_clock_getres): New method.
(timetick2dblnum_reciprocal): New function. -
configure.in: Check clock_getres.
[ruby-core:56780] [Feature #8809] accepted at
DevelopersMeeting20130831Japan
https://bugs.ruby-lang.org/projects/ruby/wiki/DevelopersMeeting20130831Japan
Updated by Eregon (Benoit Daloze) over 4 years ago
- Related to Bug #16740: Deprecating and removing the broken Process.clock_getres added
Updated by Eregon (Benoit Daloze) over 4 years ago
In #16740 I propose to remove this API because it almost always returns incorrect and useless values.