Messages in this thread | | | Date | Tue, 03 Jul 2012 23:23:52 -0700 | From | John Stultz <> | Subject | Re: [PATCH 0/3][RFC] Fix for leapsecond caused futex issue (v4) |
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On 07/03/2012 11:21 PM, John Stultz wrote: > Ok, made a few tweaks to address issues caught by Prarit's and my > testing. This has run for a number of hours now w/ my leap-a-day.c > test on a few machines. > > I'd really appreciate any extra testing, review, or acks at this point. > I'm targeting mid-late Thursday (to give folks in the US a chance to > review & test) as a point when I'll submit this upstream if no other > issues are found.
And again, here's my leap-a-day.c test case which can be used to trigger a leapsecond every day, or every ~13 seconds via the -s option.
thanks -john
/* Leap second stress test * by: john stultz (johnstul@us.ibm.com) * (C) Copyright IBM 2012 * Licensed under the GPLv2 * * This test signals the kernel to insert a leap second * every day at midnight GMT. This allows for stessing the * kernel's leap-second behavior, as well as how well applications * handle the leap-second discontinuity. * * Usage: leap-a-day [-s] * * Options: * -s: Each iteration, set the date to 10 seconds before midnight GMT. * This speeds up the number of leapsecond transitions tested, * but because it calls settimeofday frequently, advancing the * time by 24 hours every ~16 seconds, it may cause application * disruption. * * Other notes: Disabling NTP prior to running this is advised, as the two * may conflict in thier commands to the kernel. * * To build: * $ gcc leap-a-day.c -o leap-a-day -lrt */
#include <stdio.h> #include <stdlib.h> #include <time.h> #include <sys/time.h> #include <sys/timex.h> #include <string.h> #include <signal.h>
#define NSEC_PER_SEC 1000000000ULL
/* returns 1 if a <= b, 0 otherwise */ static inline int in_order(struct timespec a, struct timespec b) { if(a.tv_sec < b.tv_sec) return 1; if(a.tv_sec > b.tv_sec) return 0; if(a.tv_nsec > b.tv_nsec) return 0; return 1; }
struct timespec timespec_add(struct timespec ts, unsigned long long ns) { ts.tv_nsec += ns; while(ts.tv_nsec >= NSEC_PER_SEC) { ts.tv_nsec -= NSEC_PER_SEC; ts.tv_sec++; } return ts; }
char* time_state_str(int state) { switch (state) { case TIME_OK: return "TIME_OK"; case TIME_INS: return "TIME_INS"; case TIME_DEL: return "TIME_DEL"; case TIME_OOP: return "TIME_OOP"; case TIME_WAIT: return "TIME_WAIT"; case TIME_BAD: return "TIME_BAD"; } return "ERROR"; }
/* clear NTP time_status & time_state */ void clear_time_state(void) { struct timex tx; int ret;
/* * XXX - The fact we have to call this twice seems * to point to a slight issue in the kernel's ntp state * managment. Needs to be investigated further. */
tx.modes = ADJ_STATUS; tx.status = STA_PLL; ret = adjtimex(&tx);
tx.modes = ADJ_STATUS; tx.status = 0; ret = adjtimex(&tx); }
/* Make sure we cleanup on ctrl-c */ void handler(int unused) { clear_time_state(); exit(0); }
/* Test for known hrtimer failure */ void test_hrtimer_failure(void) { struct timespec now, target;
clock_gettime(CLOCK_REALTIME, &now); target = timespec_add(now, NSEC_PER_SEC/2); clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &target, NULL); clock_gettime(CLOCK_REALTIME, &now);
if (!in_order(target, now)) { printf("Note: hrtimer early expiration failure observed.\n"); }
}
int main(int argc, char** argv) { struct timeval tv; struct timex tx; struct timespec ts; int settime = 0;
signal(SIGINT, handler); signal(SIGKILL, handler); printf("This runs continuously. Press ctrl-c to stop\n");
/* Process arguments */ if (argc > 1) { if (!strncmp(argv[1], "-s", 2)) { printf("Setting time to speed up testing\n"); settime = 1; } else { printf("Usage: %s [-s]\n", argv[0]); printf(" -s: Set time to right before leap second each iteration\n"); } }
printf("\n"); while (1) { int ret; time_t now, next_leap; /* Get the current time */ gettimeofday(&tv, NULL);
/* Calculate the next possible leap second 23:59:60 GMT */ tv.tv_sec += 86400 - (tv.tv_sec % 86400); next_leap = ts.tv_sec = tv.tv_sec;
if (settime) { tv.tv_sec -= 10; settimeofday(&tv, NULL); printf("Setting time to %s", ctime(&ts.tv_sec)); }
/* Reset NTP time state */ clear_time_state();
/* Set the leap second insert flag */ tx.modes = ADJ_STATUS; tx.status = STA_INS; ret = adjtimex(&tx); if (ret) { printf("Error: Problem setting STA_INS!: %s\n", time_state_str(ret)); return -1; }
/* Validate STA_INS was set */ ret = adjtimex(&tx); if (tx.status != STA_INS) { printf("Error: STA_INS not set!: %s\n", time_state_str(ret)); return -1; }
printf("Scheduling leap second for %s", ctime(&next_leap)); /* Wake up 3 seconds before leap */ ts.tv_sec -= 3; while(clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &ts, NULL)) printf("Something woke us up, returning to sleep\n");
/* Validate STA_INS is still set */ ret = adjtimex(&tx); if (tx.status != STA_INS) { printf("Something cleared STA_INS, setting it again.\n"); tx.modes = ADJ_STATUS; tx.status = STA_INS; ret = adjtimex(&tx); }
/* Check adjtimex output every half second */ now = tx.time.tv_sec; while (now < next_leap+2) { char buf[26]; ret = adjtimex(&tx);
ctime_r(&tx.time.tv_sec, buf); buf[strlen(buf)-1] = 0; /*remove trailing\n */
printf("%s + %6ld us\t%s\n", buf, tx.time.tv_usec, time_state_str(ret)); now = tx.time.tv_sec; /* Sleep for another half second */ ts.tv_sec = 0; ts.tv_nsec = NSEC_PER_SEC/2; clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL); }
/* Note if kernel has known hrtimer failure */ test_hrtimer_failure();
printf("Leap complete\n\n"); }
clear_time_state(); return 0; }
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