* Re: Running POSIX Timers tests against HRT implementation
[not found] <D9223EB959A5D511A98F00508B68C20C0CCC1F7D@orsmsx108.jf.intel.com>
@ 2002-11-22 19:01 ` george anzinger
0 siblings, 0 replies; 4+ messages in thread
From: george anzinger @ 2002-11-22 19:01 UTC (permalink / raw)
To: Fleischer, Julie N, high-res-timers-discourse,
linux-kernel@vger.kernel.org
"Fleischer, Julie N" wrote:
>
> George -
> Thanks to your help in getting the bk2 kernel patches, I am finally able to
> run the POSIX Timers suite against your latest patches.
>
> I think I may be finding some conformance issues that would interest you,
> and I'm wondering how you would want me to communicate these? From people
> here, I hear patches are submitted by sending a mail to the owner and cc'ing
> the project mailing list and LKML. But, these aren't patches, since I'm
> just finding the issues, but not fixing them (Or, at least, I don't have
> that ability to yet....).
>
> I've attached an example of the types of reports I might generate (This is
> actually the one issue I've found that I've actually investigated enough to
> feel comfortable reporting it.). I just wanted to check with you first to
> know how to get this kind of information to you (if you think it is useful).
> Also, any input you have on how I could make these reports more useful would
> be appreciated.
This report is more than enough. You can report them to me
and the two mailing lists. This gives me a framework from
which to respond without folks wondering "what is this
about".
Now, as to this particular issue, the 1003.1b-1993 standard
in paragraph 14.2.1.2 says "The effect of setting a clock
via clock_settime() on armed per process timers associated
with that clock is implementation defined."
I took the easy way out here and did not choose to correct
absolute timers on clock setting. I did, however, follow
the standard on the clock_nanosleep() call where the
standard is not so forgiving.
Even here, I am afraid is fudged a little. Clock_realtime
is just the standard linux wall clock (i.e. gettimeofday())
which is changed by the NTP stuff. I do not requeue
clock_nanosleep() absolute times when NTP changes the
clock. I am would like the long range solution to this
problem to be that NTP affects CLOCK_MONOTONIC and that
CLOCK_REALTIME would then be a fixed offset from this
clock. Clock_settime() would then just mess with this
offset. This would fix other time issues in the kernel
having to do with differences between the timer clock
(CLOCK_MONOTONIC) and the wall clock.
-g
>
> Thanks.
> - Julie
>
> ======
> REPORT
> ======
> Absolute timers appear to be behaving like relative timers if the clock is
> changed using clock_settime() before the absolute timer expires.
>
> Additional information is below:
> kernel used = 2.5.48-bk2
> HRT patches applied =
> hrtimers-core-2.5.48-bk2-1.0.patch
> hrtimers-hrposix-2.5.48-bk2-1.0.patch
> hrtimers-i386-2.5.48-bk2-1.0.patch
> hrtimers-posix-2.5.48-bk2-1.0.patch
> hrtimers-support-2.5.44-1.0.patch
> hardware = Dual P3, STL2 motherboard,
> 933MHz, 512 RAM
> relevant lines of .config =
> CONFIG_HIGH_RES_TIMERS=y
> # CONFIG_HIGH_RES_TIMER_ACPI_PM is not set
> CONFIG_HIGH_RES_TIMER_TSC=y
> # CONFIG_HIGH_RES_TIMER_PIT is not set
>
> The two test cases which reproduce this issue are below (I believe these
> test cases are valid, but I'd appreciate hearing if I'm doing anything
> incorrectly.):
>
> 4-1.c - Creates an absolute timer. Moves the clock forward. Waits for the
> timer to expire. ==> The timer expires afer the relative amount of time has
> passed, not at the absolute time the timer was set to as expected per POSIX
> 1003.1-2001, lines 6004-6006.
>
> 4-2.c - Creates an absolute timer. Moves the clock forward past the time
> the timer would
> expire. ==> The timer expires after the relative amount of time has passed,
> not immeidiately as expected per POSIX 1003.1-2001, lines 6007-6009.
>
> Compiled with:
> gcc -g -O2 -Wall -Werror 4-1.c -L/lib/libposixtime.so -lposixtime
>
> Test source available on-line at:
> http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/
> posixtest/posixtestsuite/conformance/
> behavior/clock_settime/
>
> Tests
> -----
> 4-1.c
> /*
> * Copyright (c) 2002, Intel Corporation. All rights reserved.
> * Created by: julie.n.fleischer REMOVE-THIS AT intel DOT com
> * This file is licensed under the GPL license. For the full content
> * of this license, see the COPYING file at the top level of this
> * source tree.
> *
> * Test that if clock_settime() changes the value for CLOCK_REALTIME,
> * then any absolute timers will use the new time for expiration.
> *
> * Steps:
> * - get time T0
> * - create/enable a timer to expire at T1 = T0 + TIMEROFFSET
> * - sleep SLEEPTIME seconds (SLEEPTIME should be < TIMEROFFSET,
> * but > ACCEPTABLEDELTA)
> * - set time back to T0
> * - wait for the timer to expire
> * - get time T2
> * - ensure that: T2 >= T1 and (T2-T1) <= ACCEPTABLEDELTA
> *
> * signal SIGTOTEST is used.
> */
> #include <stdio.h>
> #include <time.h>
> #include <signal.h>
> #include <unistd.h>
>
> #define PASS 0
> #define FAIL 1
> #define UNRESOLVED 2
>
> // SLEEPTIME < TIMEROFFSET
> // SLEEPTIME > ACCEPTABLEDELTA
> #define SLEEPTIME 3
> #define TIMEROFFSET 9
> #define ACCEPTABLEDELTA 1
>
> #define SIGTOTEST SIGALRM
>
> int main(int argc, char *argv[])
> {
> struct sigevent ev;
> struct timespec tpT0, tpT2;
> struct itimerspec its;
> timer_t tid;
> int delta;
> int sig;
> sigset_t set;
> int flags = 0;
>
> /*
> * set up sigevent for timer
> * set up signal set for sigwait
> */
> ev.sigev_notify = SIGEV_SIGNAL;
> ev.sigev_signo = SIGTOTEST;
>
> if (sigemptyset(&set) != 0) {
> perror("sigemptyset() was not successful\n");
> return UNRESOLVED;
> }
>
> if (sigaddset(&set, SIGTOTEST) != 0) {
> perror("sigaddset() was not successful\n");
> return UNRESOLVED;
> }
>
> if (clock_gettime(CLOCK_REALTIME, &tpT0) != 0) {
> perror("clock_gettime() was not successful\n");
> return UNRESOLVED;
> }
>
> if (timer_create(CLOCK_REALTIME, &ev, &tid) != 0) {
> perror("timer_create() did not return success\n");
> return UNRESOLVED;
> }
>
> flags |= TIMER_ABSTIME;
> its.it_interval.tv_sec = 0;
> its.it_interval.tv_nsec = 0;
> its.it_value.tv_sec = tpT0.tv_sec + TIMEROFFSET;
> its.it_value.tv_nsec = tpT0.tv_nsec;
> if (timer_settime(tid, flags, &its, NULL) != 0) {
> perror("timer_settime() did not return success\n");
> return UNRESOLVED;
> }
>
> sleep(SLEEPTIME);
> if (clock_settime(CLOCK_REALTIME, &tpT0) != 0) {
> printf("clock_settime() was not successful\n");
> return UNRESOLVED;
> }
>
> if (sigwait(&set, &sig) == -1) {
> perror("sigwait() was not successful\n");
> return UNRESOLVED;
> }
>
> if (clock_gettime(CLOCK_REALTIME, &tpT2) != 0) {
> printf("clock_gettime() was not successful\n");
> return UNRESOLVED;
> }
>
> delta = tpT2.tv_sec - its.it_value.tv_sec;
>
> if ( (delta <= ACCEPTABLEDELTA) && (delta >= 0) ) {
> printf("Test PASSED\n");
> return PASS;
> } else {
> printf("FAIL: Ended %d, not %d\n",
> (int) tpT2.tv_sec,
> (int) its.it_value.tv_sec);
> return FAIL;
> }
>
> return UNRESOLVED;
> }
>
> 4-2.c
> /*
> * Copyright (c) 2002, Intel Corporation. All rights reserved.
> * Created by: julie.n.fleischer REMOVE-THIS AT intel DOT com
> * This file is licensed under the GPL license. For the full content
> * of this license, see the COPYING file at the top level of this
> * source tree.
> *
> * Test that if clock_settime() changes the value for CLOCK_REALTIME,
> * an absolute timer which would now have expired in the past
> * will expire immediately (with no error).
> *
> * Steps:
> * - get time T0
> * - create/enable a timer to expire at T1 = T0 + TIMEROFFSET
> * - set time forward to T1 + CLOCKOFFSET
> * - ensure that timer has expired with no error
> *
> * signal SIGTOTEST is used.
> */
> #include <stdio.h>
> #include <time.h>
> #include <signal.h>
> #include <unistd.h>
> #include <stdlib.h>
>
> #define PASS 0
> #define FAIL 1
> #define UNRESOLVED 2
>
> // SLEEPTIME < TIMEROFFSET
> // SLEEPTIME > ACCEPTABLEDELTA
> #define TIMEROFFSET 9
> #define CLOCKOFFSET 4
>
> #define SHORTTIME 1
>
> #define SIGTOTEST SIGALRM
>
> void handler(int signo)
> {
> printf("Caught signal\n");
> printf("Test PASSED\n");
> exit(PASS);
> }
>
> int main(int argc, char *argv[])
> {
> struct sigevent ev;
> struct sigaction act;
> struct timespec tpT0, tpclock;
> struct itimerspec its;
> timer_t tid;
> //int sig;
> sigset_t set;
> int flags = 0;
>
> /*
> * set up sigevent for timer
> * set up signal set for sigwait
> * set up sigaction to catch signal
> */
> ev.sigev_notify = SIGEV_SIGNAL;
> ev.sigev_signo = SIGTOTEST;
>
> act.sa_handler=handler;
> act.sa_flags=0;
>
> if ( (sigemptyset(&set) != 0) ||
> (sigemptyset(&act.sa_mask) != 0) ) {
> perror("sigemptyset() was not successful\n");
> return UNRESOLVED;
> }
>
> if (sigaddset(&set, SIGTOTEST) != 0) {
> perror("sigaddset() was not successful\n");
> return UNRESOLVED;
> }
>
> if (sigaction(SIGTOTEST, &act, 0) != 0) {
> perror("sigaction() was not successful\n");
> return UNRESOLVED;
> }
>
> if (clock_gettime(CLOCK_REALTIME, &tpT0) != 0) {
> perror("clock_gettime() was not successful\n");
> return UNRESOLVED;
> }
>
> if (timer_create(CLOCK_REALTIME, &ev, &tid) != 0) {
> perror("timer_create() did not return success\n");
> return UNRESOLVED;
> }
>
> flags |= TIMER_ABSTIME;
> its.it_interval.tv_sec = 0;
> its.it_interval.tv_nsec = 0;
> its.it_value.tv_sec = tpT0.tv_sec + TIMEROFFSET;
> its.it_value.tv_nsec = tpT0.tv_nsec;
> if (timer_settime(tid, flags, &its, NULL) != 0) {
> perror("timer_settime() did not return success\n");
> return UNRESOLVED;
> }
>
> tpclock.tv_sec = its.it_value.tv_sec + CLOCKOFFSET;
> tpclock.tv_nsec = its.it_value.tv_nsec;
> if (clock_settime(CLOCK_REALTIME, &tpclock) != 0) {
> printf("clock_settime() was not successful\n");
> return UNRESOLVED;
> }
>
> sleep(SHORTTIME);
> printf("timer should have expired _immediately_\n");
> return FAIL;
> }
> **These views are not necessarily those of my employer.**
--
George Anzinger george@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
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