On 02-Oct-16 19:50, Michael Felt wrote:
class perfstat_cpu_total_t(Structure):
"""
typedef struct { /* global cpu information */
int ncpus; /* number of active logical
processors */
int ncpus_cfg; /* number of configured processors */
char description[IDENTIFIER_LENGTH]; /* processor description
(type/official name) */
u_longlong_t buffer1[15]; /* several variables being
skipped for now */
time_t lbolt; /* number of ticks since last
reboot */
u_longlong_t loadavg[3]; /* (1<<SBITS) times the average
number of runnables processes during the last
1, 5 and 15 minutes. */
u_longlong_t buffer2[29]; /* several variables being
skipped for now */
int ncpus_high; /* index of highest processor online */
u_longlong_t puser; /* raw number of physical processor
tics in user mode */
u_longlong_t psys; /* raw number of physical processor
tics in system mode */
u_longlong_t pidle; /* raw number of physical processor
tics idle */
u_longlong_t pwait; /* raw number of physical processor
tics waiting for I/O */
u_longlong_t buffer2[29]; /* several variables being
skipped for now */
} perfstat_cpu_total_t;
"""
_fields_ = [
("ncpus", c_int),
("ncpus_cfg", c_int),
("description", c_char * IDENTIFIER_LENGTH),
("buffer1", c_ulonglong * 15),
("lbolt", time_t),
("loadavg", c_ulonglong * 3),
("buffer2", c_ulonglong * 29),
("ncpus_high", c_int),
("puser", c_ulonglong),
("psys", c_ulonglong),
("pidle", c_ulonglong),
("pwait", c_ulonglong),
("buffer3", c_ulonglong * 12)
]
Perhaps I should explain what I want to accomplish.
a) use ctypes.CDLL to open libperfstat.a(shr_64.o)
b) call a number for functions, among them
The prototype template (in C) is:
The common signature used by all of the global interfaces is as follows:
int perfstat_subsystem_total(
perfstat_id_t *name,
perfstat_subsystem_total_t *userbuff,
int sizeof_struct,
int desired_number);
The usage of the parameters for all of the interfaces is as follows:
perfstat_id_t *name Reserved for future use, should be NULL
perfstat_subsystem_total_t *userbuff A pointer to a memory area with
enough space for the returned structure
int sizeof_struct Should be set to sizeof(perfstat_subsystem_t)
int desired_number Reserved for future use, must be set to 0 or 1
The return value will be -1 in case of errors. Otherwise, the number of
structures copied is returned. This
is always 1.
So, in C the call looks something like this - for cpu_total
perfstat_cpu_total(NULL, (struct perfstat_cpu_total_t *) &xxx,
sizeof(perfstat_cpu_total_t), 1)
I am struggling with the declarations needed to make the call
I have several iterations - the most simple case (no CFUNCTYPE declaration)
gives
+79 class cpu_total:
+80 def __init__(self):
+81 __perfstat__ = CDLL("libperfstat.a(shr_64.o)")
+82 xxx = perfstat_cpu_total_t
+83 cpu_total = __perfstat__.perfstat_cpu_total
+84 ret = cpu_total(None, xxx, sizeof(xxx), 1)
+85 print xxx.ncpus
+86 print xxx.lbolt.v
+87
+88 a = cpu_total()
!cat test_1.py | python
Traceback (most recent call last):
File "<stdin>", line 88, in <module>
File "<stdin>", line 84, in __init__
ctypes.ArgumentError: argument 2: <type 'exceptions.TypeError'>: Don't know how
to convert parameter 2
I have tried some experiments with CFUNCTYPE - basically
prototype = CFUNCTYPE(c_int, c_void_p, c_int, c_int, c_int)
but I do not understand how (I think some of the details are missing from the
example) how the following works:
I have also tried:
+80 def __init__(self):
+81 __perfstat__ = CDLL("libperfstat.a(shr_64.o)")
+82 xxx = perfstat_cpu_total_t
+83 xptr = POINTER(xxx)
+84 x2 = cast(xptr,POINTER(c_void_p))
+85 cpu_total = __perfstat__.perfstat_cpu_total
+86 ret = cpu_total(None, x2, sizeof(xxx), 1)
+87 print xxx.ncpus
+88 print xxx.lbolt.v
+89
+90 a = cpu_total()
+91 print sizeof(a)
!cat test_1.py | python
Traceback (most recent call last):
File "<stdin>", line 90, in <module>
File "<stdin>", line 84, in __init__
File "/opt/lib/python2.7/ctypes/__init__.py", line 509, in cast
return _cast(obj, obj, typ)
ctypes.ArgumentError: argument 1: <type 'exceptions.TypeError'>: wrong type
+79 class cpu_total:
+80 def __init__(self):
+81 __perfstat__ = CDLL("libperfstat.a(shr_64.o)")
+82 xxx = perfstat_cpu_total_t
+83 xptr = POINTER(xxx)
+84 cpu_total = __perfstat__.perfstat_cpu_total
+85 ret = cpu_total(None, xptr, sizeof(xxx), 1)
+86 print xxx.ncpus
+87 print xxx.lbolt.v
+88
+89 a = cpu_total()
+90 print sizeof(a)
+91
!cat test_1.py | python
Traceback (most recent call last):
File "<stdin>", line 89, in <module>
File "<stdin>", line 85, in __init__
ctypes.ArgumentError: argument 2: <type 'exceptions.TypeError'>: Don't know how
to convert parameter 2
and
+79 class cpu_total:
+80 def __init__(self):
+81 __perfstat__ = CDLL("libperfstat.a(shr_64.o)")
+82 xxx = perfstat_cpu_total_t
+83 xptr = c_void_p(xxx)
+84 cpu_total = __perfstat__.perfstat_cpu_total
+85 ret = cpu_total(None, xptr, sizeof(xxx), 1)
+86 print xxx.ncpus
+87 print xxx.lbolt.v
+88
+89 a = cpu_total()
+90 print sizeof(a)
+91
!cat test_1.py | python
Traceback (most recent call last):
File "<stdin>", line 89, in <module>
File "<stdin>", line 83, in __init__
TypeError: cannot be converted to pointer
I know they are "stabs in the dark" as I really do not grasp the documentation.
Maybe it is clear to someone well versed in python, or just smarter than I.
Your expert assistance is appreciated!
--
https://mail.python.org/mailman/listinfo/python-list
