----- "Garrett Cooper" <[email protected]> wrote:
> On Sun, Jul 18, 2010 at 11:55 PM, Caspar Zhang <[email protected]>
> wrote:
> >
> > ----- "Garrett Cooper" <[email protected]> wrote:
> >
> >>
> >> The fact that the test is using time(3) to calculate the
> elapsed
> >> period instead of clock_gettime is dubious at best, because the
> >> precision of time is in seconds. Maybe it should be converted to
> >> clock_gettime calls for improved precision?
> >
> > Use clock_gettime instead of time(3), patch attached.
>
> Looks better, but being strict it's still buggy. POSIX defines struct
> timespec as:
>
> The <time.h> header shall declare the structure timespec, which has
> at
> least the following members:
>
> time_t tv_sec Seconds.
> long tv_nsec Nanoseconds.
>
> So you're losing precision in one case, and time_t can be variable
> (the spec for types.h is rather fluid):
>
> time_t and clock_t shall be integer or real-floating types.
>
> The (struct timeval *) casts are also unnecessary because you're
> getting the address of a struct timeval object (which is in both
> cases
> struct timeval*).
>
> > Another question, since POSIX.1-2008 marks gettimeofday() as
> obsolete
> > (man gettimeofday), should the usec test part be changed to
> > clock_getime as well?
>
> Sure, if you want.
Updated patch, FYI.
Thanks,
Caspar
Hi all,
1. In my recent tests, not all desired time be equal to exact execution
time in sec test part, use clock_gettime to improve precision.
2. gettimeofday is marked as obsolete in POSIX.1-2008 according to
man gettimeofday, so change gettimeofday to clock_gettime in nsec test
part.
Signed-off-by: Caspar Zhang <[email protected]>
diff -Naur a/testcases/kernel/syscalls/pselect/Makefile
b/testcases/kernel/syscalls/pselect/Makefile
--- a/testcases/kernel/syscalls/pselect/Makefile 2010-04-01
14:23:10.000000000 +0800
+++ b/testcases/kernel/syscalls/pselect/Makefile 2010-07-19
14:54:38.984482305 +0800
@@ -21,6 +21,7 @@
include $(top_srcdir)/include/mk/testcases.mk
include $(abs_srcdir)/../utils/newer_64.mk
+LDLIBS += -lpthread -lrt
%_64: CPPFLAGS += -D_FILE_OFFSET_BITS=64
include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff -Naur a/testcases/kernel/syscalls/pselect/pselect01.c
b/testcases/kernel/syscalls/pselect/pselect01.c
--- a/testcases/kernel/syscalls/pselect/pselect01.c 2010-04-01
14:23:10.000000000 +0800
+++ b/testcases/kernel/syscalls/pselect/pselect01.c 2010-07-19
16:08:32.402482397 +0800
@@ -61,14 +61,12 @@
int main()
{
- int ret_pselect, total_sec, fd, total_nsec;
+ int ret_pselect, fd;
fd_set readfds;
- struct timespec tv;
int retval;
- time_t t;
- unsigned start, end;
- struct timeval tv_start, tv_end;
- int real_usec;
+ struct timespec tv, tv_start, tv_end;
+ long real_nsec, total_nsec;
+ int real_sec, total_sec;
setup();
@@ -103,17 +101,20 @@
tst_resm(TINFO,
"Testing basic pselect sanity,Sleeping for %jd secs",
(intmax_t)tv.tv_sec);
- start = time(&t);
+ clock_gettime(CLOCK_REALTIME, &tv_start);
retval =
- pselect(0, &readfds, NULL, NULL, (struct timespec *)&tv,
+ pselect(0, &readfds, NULL, NULL, &tv,
NULL);
- end = time(&t);
+ clock_gettime(CLOCK_REALTIME, &tv_end);
- if (((end - start) == total_sec) || ((end - start) == total_sec
+ 1))
+ /* do a rounding */
+ real_sec = (int)(0.5 + (tv_end.tv_sec - tv_start.tv_sec +
+ 1e-9 * (tv_end.tv_nsec - tv_start.tv_nsec)));
+ if (real_sec == total_sec)
tst_resm(TPASS, "Sleep time was correct");
else
tst_resm(TFAIL, "Sleep time was incorrect:%d != %d",
- total_sec, (end - start));
+ total_sec, real_sec);
}
#ifdef DEBUG
@@ -129,19 +130,19 @@
tst_resm(TINFO,
"Testing basic pselect sanity,Sleeping for %ld nano
secs",
tv.tv_nsec);
- gettimeofday(&tv_start, NULL);
+ clock_gettime(CLOCK_REALTIME, &tv_start);
retval =
pselect(0, &readfds, NULL, NULL, &tv,
NULL);
- gettimeofday(&tv_end, NULL);
+ clock_gettime(CLOCK_REALTIME, &tv_end);
/* Changed total_sec compare to an at least vs an exact compare
*/
- real_usec = (tv_end.tv_sec - tv_start.tv_sec) * 1e6 +
- tv_end.tv_usec - tv_start.tv_usec;
+ real_nsec = (tv_end.tv_sec - tv_start.tv_sec) * 1e9 +
+ tv_end.tv_nsec - tv_start.tv_nsec;
/* allow 10% error*/
- if (abs(real_usec - tv.tv_nsec / 1000) < 0.1 * total_nsec /
1000)
+ if (abs(real_nsec - tv.tv_nsec) < 0.1 * total_nsec)
tst_resm(TPASS, "Sleep time was correct");
else {
tst_resm(TWARN,
@@ -150,8 +151,8 @@
"due to the limitation of the way it
calculates the");
tst_resm(TWARN, "system call execution time.");
tst_resm(TFAIL,
- "Sleep time was incorrect:%d usec vs expected
%d usec",
- real_usec, total_nsec / 1000);
+ "Sleep time was incorrect:%ld nsec vs expected
%ld nsec",
+ real_nsec, total_nsec);
}
}
cleanup();
--
Kernel Associate Quality Engineer
Red Hat Inc. (Beijing R&D Branch)
Red Hat China R&D Branch Unit 907, North Tower C,
Raycom Infotech Park, No.2 Kexueyuan Nanlu,
Haidian District, Beijing 100190
TEL: +86-10-62608150
Web: http://www.redhat.com/
Hi all,
1. In my recent tests, not all desired time be equal to exact execution
time in sec test part, use clock_gettime to improve precision.
2. gettimeofday is marked as obsolete in POSIX.1-2008 according to
man gettimeofday, so change gettimeofday to clock_gettime in nsec test
part.
Signed-off-by: Caspar Zhang <[email protected]>
diff -Naur a/testcases/kernel/syscalls/pselect/Makefile b/testcases/kernel/syscalls/pselect/Makefile
--- a/testcases/kernel/syscalls/pselect/Makefile 2010-04-01 14:23:10.000000000 +0800
+++ b/testcases/kernel/syscalls/pselect/Makefile 2010-07-19 14:54:38.984482305 +0800
@@ -21,6 +21,7 @@
include $(top_srcdir)/include/mk/testcases.mk
include $(abs_srcdir)/../utils/newer_64.mk
+LDLIBS += -lpthread -lrt
%_64: CPPFLAGS += -D_FILE_OFFSET_BITS=64
include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff -Naur a/testcases/kernel/syscalls/pselect/pselect01.c b/testcases/kernel/syscalls/pselect/pselect01.c
--- a/testcases/kernel/syscalls/pselect/pselect01.c 2010-04-01 14:23:10.000000000 +0800
+++ b/testcases/kernel/syscalls/pselect/pselect01.c 2010-07-19 16:08:32.402482397 +0800
@@ -61,14 +61,12 @@
int main()
{
- int ret_pselect, total_sec, fd, total_nsec;
+ int ret_pselect, fd;
fd_set readfds;
- struct timespec tv;
int retval;
- time_t t;
- unsigned start, end;
- struct timeval tv_start, tv_end;
- int real_usec;
+ struct timespec tv, tv_start, tv_end;
+ long real_nsec, total_nsec;
+ int real_sec, total_sec;
setup();
@@ -103,17 +101,20 @@
tst_resm(TINFO,
"Testing basic pselect sanity,Sleeping for %jd secs",
(intmax_t)tv.tv_sec);
- start = time(&t);
+ clock_gettime(CLOCK_REALTIME, &tv_start);
retval =
- pselect(0, &readfds, NULL, NULL, (struct timespec *)&tv,
+ pselect(0, &readfds, NULL, NULL, &tv,
NULL);
- end = time(&t);
+ clock_gettime(CLOCK_REALTIME, &tv_end);
- if (((end - start) == total_sec) || ((end - start) == total_sec + 1))
+ /* do a rounding */
+ real_sec = (int)(0.5 + (tv_end.tv_sec - tv_start.tv_sec +
+ 1e-9 * (tv_end.tv_nsec - tv_start.tv_nsec)));
+ if (real_sec == total_sec)
tst_resm(TPASS, "Sleep time was correct");
else
tst_resm(TFAIL, "Sleep time was incorrect:%d != %d",
- total_sec, (end - start));
+ total_sec, real_sec);
}
#ifdef DEBUG
@@ -129,19 +130,19 @@
tst_resm(TINFO,
"Testing basic pselect sanity,Sleeping for %ld nano secs",
tv.tv_nsec);
- gettimeofday(&tv_start, NULL);
+ clock_gettime(CLOCK_REALTIME, &tv_start);
retval =
pselect(0, &readfds, NULL, NULL, &tv,
NULL);
- gettimeofday(&tv_end, NULL);
+ clock_gettime(CLOCK_REALTIME, &tv_end);
/* Changed total_sec compare to an at least vs an exact compare */
- real_usec = (tv_end.tv_sec - tv_start.tv_sec) * 1e6 +
- tv_end.tv_usec - tv_start.tv_usec;
+ real_nsec = (tv_end.tv_sec - tv_start.tv_sec) * 1e9 +
+ tv_end.tv_nsec - tv_start.tv_nsec;
/* allow 10% error*/
- if (abs(real_usec - tv.tv_nsec / 1000) < 0.1 * total_nsec / 1000)
+ if (abs(real_nsec - tv.tv_nsec) < 0.1 * total_nsec)
tst_resm(TPASS, "Sleep time was correct");
else {
tst_resm(TWARN,
@@ -150,8 +151,8 @@
"due to the limitation of the way it calculates the");
tst_resm(TWARN, "system call execution time.");
tst_resm(TFAIL,
- "Sleep time was incorrect:%d usec vs expected %d usec",
- real_usec, total_nsec / 1000);
+ "Sleep time was incorrect:%ld nsec vs expected %ld nsec",
+ real_nsec, total_nsec);
}
}
cleanup();
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