Very Computer

[problem]

In my code like following, using select() and an application as linked
pthread lib.
If I change date, application*.

(sample code)
#include <stdio.h>
#include <sys/time.h>

int
main()
{
    struct timeval timeout;
    int cnt;

    for(cnt=0;;cnt++) {
#if 1
        timeout.tv_sec  = 5;
        timeout.tv_usec = 0;
        select(0,0,0,0,&timeout);
#else
        sleep(5);
#endif
        printf("[%d] Wakeup \n",cnt);
    }

Quote:}

(compile & link)
cc -o test_sleep test_sleep.c -lpthread

(If I change date at another terminal like "date 0101010102", sample code is
blocked)

I think this problem can solve with some kernel patch.

Somebody help me~ T_T

Was it like that, or was it that?

I don't believe Sun makes any promises about Solaris being stable in the
face of backward timeshifts.  You can completely fill up the TCP socket
table by doing that.

Quote:> I think this problem can solve with some kernel patch.

Why do you need your code to work when the clock goes backward?

--

Unix System Administrator                    Taos - The SysAdmin Company
Got some Dr Pepper?                           San Francisco, CA bay area
         < This line left intentionally blank to confuse you. >

was it that.... ^^;

I need study english harder.

Quote:

> I don't believe Sun makes any promises about Solaris being stable in the
> face of backward timeshifts.  You can completely fill up the TCP socket
> table by doing that.

> > I think this problem can solve with some kernel patch.

> Why do you need your code to work when the clock goes backward?

my system using NTP.

if system clock goes fast, NTP will backward the clock.

I'm worry about that.

If that is occured, my application will stoped.

I don't wanna occur*.

Thank you for your reply.

PS : Have a good day~

        NTP does not use `date' to change the date (I believe it uses
        adjtime), except possibly when first started (and there are ways
        to avoid a sudden time shift when first starting NTP, which should be
        in the NTP documentation).

        There are -many- applications that use select/poll which work just
        fine with NTP so unless you do something strange you should not have a
        problem.

        m.

I was asking if your "date" string was just a sample, or if you really
set the clock back by over a year?

Quote:

>> I don't believe Sun makes any promises about Solaris being stable in the
>> face of backward timeshifts.  You can completely fill up the TCP socket
>> table by doing that.

>> > I think this problem can solve with some kernel patch.

>> Why do you need your code to work when the clock goes backward?

> my system using NTP.
> if system clock goes fast, NTP will backward the clock.

Maybe by a second or two.  You've set your clock back by over a year.
That's very different.

Do you need to set your clock back by more than a few seconds for any
reason?

--

Unix System Administrator                    Taos - The SysAdmin Company
Got some Dr Pepper?                           San Francisco, CA bay area
         < This line left intentionally blank to confuse you. >

nope. If NTP change system clock, maybe it's just one or two second.
I would not change the clock by "date" command.
NTP will change the system clock.

Quote:

> >> I don't believe Sun makes any promises about Solaris being stable in
the
> >> face of backward timeshifts.  You can completely fill up the TCP socket
> >> table by doing that.

> >> > I think this problem can solve with some kernel patch.

> >> Why do you need your code to work when the clock goes backward?

> > my system using NTP.

> > if system clock goes fast, NTP will backward the clock.

> Maybe by a second or two.  You've set your clock back by over a year.
> That's very different.

> Do you need to set your clock back by more than a few seconds for any
> reason?

No. ^^
I said. I do not need to change the clock.
The clock may change by only the NTP service.
So It maybe different just one or two second.
The problem is NTP can backward the clock.
Then my application will*.

If you compile my sample code and set the clock for backward
during application running, you can understand my problem so easily. ^^

I could not solve this problem.

Thank you for your care.

PS : have a HAPPY day~ ^^

How are you using NTP, then? Generally speaking, NTP will NOT step
the clock backward; it will slow the clock down so real time can
catch up.

Casper
--
Expressed in this posting are my opinions.  They are in no way related
to opinions held by my employer, Sun Microsystems.
Statements on Sun products included here are not gospel and may
be fiction rather than truth.

Yes. You're right. It's my mistake.
My code use "ntpdate" command.
So it can change the system clock to backward.

Now, can u solve this problem??

PS : have a good day~

"your code" should not be running ntpdate!
The system should be running xntpd (or ntpd) (the daemon version of ntpdate)
(common startup scripts run ntpdate to get the clock within some milliseconds.
Afterwards (x)ntpd takes over and keeps the clock acurate without jumps.)