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SubjectRe: [PATCH v4 10/12] arm64: vdso: replace gettimeofday.S with global vgettimeofday.C
On Tue, Nov 21, 2017 at 13:28:13 PST, Mark Salyzyn wrote:
> I ran the test (32 and 64 bit) on my latest work (but back-ported to
> 4.9) and it passes. I did not change __vdso_clock_getres or the fallback
> (syscall) handler in the patch series though, so the failure has me
> wondering. Could you re-run the test with latest to be sure, and I will
> look into setting up to test with a ToT kernel (after the thanksgiving
> break).


I applied your patch set to a 4.14 kernel and ran LTP clock_getres01
(64-bit) and it still passed:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[root@localhost ~]# uname -r
4.14.0-vdsogtod.aarch64

[root@localhost ~]# ./ltp-full-20170929/testcases/kernel/syscalls/clock_getres/clock_getres01
tst_test.c:934: INFO: Timeout per run is 0h 05m 00s
clock_getres01.c:79: PASS: clock_getres(REALTIME, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(MONOTONIC, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(PROCESS_CPUTIME_ID, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(THREAD_CPUTIME_ID, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(REALTIME, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(CLOCK_MONOTONIC_RAW, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(CLOCK_REALTIME_COARSE, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(CLOCK_MONOTONIC_COARSE, ...) succeeded
clock_getres01.c:79: PASS: clock_getres(CLOCK_BOOTTIME, ...) succeeded
clock_getres01.c:64: CONF: clock_getres(CLOCK_REALTIME_ALARM, ...) NO SUPPORTED
clock_getres01.c:64: CONF: clock_getres(CLOCK_BOOTTIME_ALARM, ...) NO SUPPORTED
clock_getres01.c:79: PASS: clock_getres(-1, ...) succeeded

Summary:
passed 10
failed 0
skipped 2
warnings 0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


I also tried another test (see source below) which sleeps for 0.5
seconds and then verifies that approximately 0.5 seconds passed. With
the original gettimeofday-in-C patches, it would often fail with weird
elapsed times like 0.1 seconds or 1.1 seconds:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[root@localhost ~]# ./a.out ; echo $?
1: clock_gettime: tv_sec = 1207, tv_nsec = 6403566
Sleeping 0.5 seconds
2: clock_gettime: tv_sec = 1207, tv_nsec = 16512476
Elapsed: 0.10108910
FAIL: elapsed time is not approximately 0.5 seconds
255

[root@localhost ~]# ./a.out ; echo $?
1: clock_gettime: tv_sec = 1215, tv_nsec = 9784545
Sleeping 0.5 seconds
2: clock_gettime: tv_sec = 1216, tv_nsec = 9898595
Elapsed: 1.114050
FAIL: elapsed time is not approximately 0.5 seconds
255

[root@localhost ~]# ./a.out ; echo $?
1: clock_gettime: tv_sec = 1225, tv_nsec = 13710370
Sleeping 0.5 seconds
2: clock_gettime: tv_sec = 1225, tv_nsec = 13819740
Elapsed: 0.109370
FAIL: elapsed time is not approximately 0.5 seconds
255
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


The elapsed time matches the expected 0.5 seconds with the latest patch
version:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[root@localhost ~]# ./a.out ; echo $?
1: clock_gettime: tv_sec = 2077, tv_nsec = 989623095
Sleeping 0.5 seconds
2: clock_gettime: tv_sec = 2078, tv_nsec = 489728070
Elapsed: 0.500104975
PASS
0
[root@localhost ~]# ./a.out ; echo $?
1: clock_gettime: tv_sec = 2079, tv_nsec = 519625035
Sleeping 0.5 seconds
2: clock_gettime: tv_sec = 2080, tv_nsec = 19726365
Elapsed: 0.500101330
PASS
0
[root@localhost ~]# ./a.out ; echo $?
1: clock_gettime: tv_sec = 2080, tv_nsec = 684894725
Sleeping 0.5 seconds
2: clock_gettime: tv_sec = 2081, tv_nsec = 184994605
Elapsed: 0.500099880
PASS
0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Source for the elapsed time test:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <stdio.h>
#include <time.h>

int main(void)
{
int ret;
clockid_t clk_id = CLOCK_MONOTONIC_RAW;
struct timespec tp1, tp2, elapsed;
struct timespec req, rem;

ret = clock_gettime(clk_id, &tp1);
if (ret) {
perror("ERROR: clock_gettime:");
}
printf("1: clock_gettime: tv_sec = %ld, tv_nsec = %lld\n",
tp1.tv_sec, tp1.tv_nsec);

printf("Sleeping 0.5 seconds\n");
req.tv_sec = 0;
req.tv_nsec = 500000000;
ret = nanosleep(&req, &rem);
if (ret) {
perror("ERROR: nanosleep:");
printf(" Remaining sleep: tv_sec = %ld, tv_nsec = %lld\n",
rem.tv_sec, rem.tv_nsec);
}

ret = clock_gettime(clk_id, &tp2);
if (ret) {
perror("ERROR: clock_gettime:");
}
printf("2: clock_gettime: tv_sec = %ld, tv_nsec = %lld\n",
tp2.tv_sec, tp2.tv_nsec);

if ((tp2.tv_nsec - tp1.tv_nsec) < 0) {
elapsed.tv_sec = tp2.tv_sec - tp1.tv_sec - 1;
elapsed.tv_nsec = 1000000000 + tp2.tv_nsec - tp1.tv_nsec;
} else {
elapsed.tv_sec = tp2.tv_sec - tp1.tv_sec;
elapsed.tv_nsec = tp2.tv_nsec - tp1.tv_nsec;
}

printf("Elapsed: %ld.%lld\n", elapsed.tv_sec, elapsed.tv_nsec);

if (elapsed.tv_sec != 0 ||
elapsed.tv_nsec < 490000000 ||
elapsed.tv_nsec > 510000000) {
printf("FAIL: elapsed time is not approximately 0.5 seconds\n");
return -1;
}

printf("PASS\n");
return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


--
Jeff Bastian
Kernel QE - Hardware Enablement
Red Hat

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