Re: Counting the clock cycles
In message: [EMAIL PROTECTED] Poul-Henning Kamp [EMAIL PROTECTED] writes: : Unless we want to deal properly with leapseconds and implement TAI, : we have no choice in that matter. Well, djm has libraries that keeps the system time in UTC + leapseconds and causes the right time to be displayed by tweaks to the timezone files Warner To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
Andrei Cojocaru wrote: I am already synchronizing using xntp, that's not the problem. The problem is by some weird way the clock got out of sync by about 1hr during daylight switch on one of the computers I run, and I need a reliable way to get passage of time (I don't need date/time, just the passage of it) for different internal operations in the program. Looking for another clock already living there somewhere in the same PC hardware isn't going to fix it. You need to disable CMOS daylight savings time swithing in the BIOS, so that it doesn't jump the reported clock value on you. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
Does FreeBSD do that or do I have to look for an option in the BIOS? Andrei Cojocaru [EMAIL PROTECTED] - Original Message - From: Terry Lambert [EMAIL PROTECTED] To: Andrei Cojocaru [EMAIL PROTECTED] Cc: Darren Pilgrim [EMAIL PROTECTED]; Cy Schubert - CITS Open Systems Group [EMAIL PROTECTED]; [EMAIL PROTECTED] Sent: Thursday, July 18, 2002 1:18 AM Subject: Re: Counting the clock cycles Andrei Cojocaru wrote: I am already synchronizing using xntp, that's not the problem. The problem is by some weird way the clock got out of sync by about 1hr during daylight switch on one of the computers I run, and I need a reliable way to get passage of time (I don't need date/time, just the passage of it) for different internal operations in the program. Looking for another clock already living there somewhere in the same PC hardware isn't going to fix it. You need to disable CMOS daylight savings time swithing in the BIOS, so that it doesn't jump the reported clock value on you. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
Andrei Cojocaru wrote: Looking for another clock already living there somewhere in the same PC hardware isn't going to fix it. You need to disable CMOS daylight savings time swithing in the BIOS, so that it doesn't jump the reported clock value on you. Does FreeBSD do that or do I have to look for an option in the BIOS? You need to look for an option in BIOS. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Counting the clock cycles
I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. Andrei Cojocaru [EMAIL PROTECTED] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
Andrei Cojocaru wrote: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Use the Pentium Cycle Counter. Note that power management is going to make it inaccurate as a time base. Give up on the idea that you will have a wall time that is more accurate than the CMOS clock; after you've embraced that, you can learn to stop worrying and love Intel. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
* Andrei Cojocaru [EMAIL PROTECTED] [020717 12:02] wrote: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. I don't see a platform independant way of doing this, sorry. Have a look at the source for w(1). http://www.freebsd.org/cgi/cvsweb.cgi/src/usr.bin/w/w.c Look at the function pr_header(), it uses SYSCTL to grab system uptime. -- -Alfred Perlstein [[EMAIL PROTECTED]] 'Instead of asking why a piece of software is using 1970s technology, start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
rdtsc() will give you cycle counts since system boot. It reads a Pentium internal register which is incremented at every CPU internal clock cycle. Deepankar Andrei Cojocaru wrote: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. Andrei Cojocaru [EMAIL PROTECTED] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
In message 00d501c22dc4$57d08b00$0200a8c0@twothousand, Andrei Cojocaru writ es: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. How about time(3)? -- Cheers, Phone: 250-387-8437 Cy SchubertFax: 250-387-5766 Team Leader, Sun/Alpha Team Email: [EMAIL PROTECTED] Open Systems Group, CITS Ministry of Management Services Province of BC FreeBSD UNIX: [EMAIL PROTECTED] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
doesn't fit my criteria since it changes, bah I'll just use gettimeofday since it's a portable API and hope the computers I run it on don't change their blocks by too much... - Original Message - From: Cy Schubert - CITS Open Systems Group [EMAIL PROTECTED] To: Andrei Cojocaru [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Sent: Wednesday, July 17, 2002 13:43 Subject: Re: Counting the clock cycles In message 00d501c22dc4$57d08b00$0200a8c0@twothousand, Andrei Cojocaru writ es: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. How about time(3)? -- Cheers, Phone: 250-387-8437 Cy SchubertFax: 250-387-5766 Team Leader, Sun/Alpha Team Email: [EMAIL PROTECTED] Open Systems Group, CITS Ministry of Management Services Province of BC FreeBSD UNIX: [EMAIL PROTECTED] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
Andrei Cojocaru wrote: doesn't fit my criteria since it changes, bah I'll just use gettimeofday since it's a portable API and hope the computers I run it on don't change their blocks by too much... If you're really worried about it, get a GPS device that can provide you with a PPS signal for use with ntpd. Then I'd say you could safely rely on the computer's clock being accurate. From: Cy Schubert - CITS Open Systems Group [EMAIL PROTECTED] In message 00d501c22dc4$57d08b00$0200a8c0@twothousand, Andrei Cojocaru writes: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. How about time(3)? To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
I am already synchronizing using xntp, that's not the problem. The problem is by some weird way the clock got out of sync by about 1hr during daylight switch on one of the computers I run, and I need a reliable way to get passage of time (I don't need date/time, just the passage of it) for different internal operations in the program. - Original Message - From: Darren Pilgrim [EMAIL PROTECTED] To: Andrei Cojocaru [EMAIL PROTECTED] Cc: Cy Schubert - CITS Open Systems Group [EMAIL PROTECTED]; [EMAIL PROTECTED] Sent: Wednesday, July 17, 2002 14:25 Subject: Re: Counting the clock cycles Andrei Cojocaru wrote: doesn't fit my criteria since it changes, bah I'll just use gettimeofday since it's a portable API and hope the computers I run it on don't change their blocks by too much... If you're really worried about it, get a GPS device that can provide you with a PPS signal for use with ntpd. Then I'd say you could safely rely on the computer's clock being accurate. From: Cy Schubert - CITS Open Systems Group [EMAIL PROTECTED] In message 00d501c22dc4$57d08b00$0200a8c0@twothousand, Andrei Cojocaru writes: I was asking around in #freebsdhelp on EFNet what the equivalent of GetTickCount() in the Win32 API is in FreeBSD. I need a way to properly determine passage of time that is not affected if I change the system clock for example. The only way I'm aware that you can do that is by counting the number of clock cycles since system startup. What function does that in FreeBSD? I'd also like a Linux way if possible. (that is a way that will work across all UNIX clones). Thanks and please include my email in the reply directly since I'm not signed up to this mailing list. Thanks once again. How about time(3)? To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
depending on the acuracy needed use the uptime.. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
In message 005f01c22dd1$7be7d180$0300a8c0@fivehundred, Andrei Cojocaru writ es: I am already synchronizing using xntp, that's not the problem. The problem is by some weird way the clock got out of sync by about 1hr during daylight switch on one of the computers I run, and I need a reliable way to get passage of time (I don't need date/time, just the passage of it) for different internal operations in the program. Use UTC time, it has no daylight savings problems. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
yes but how do you get the uptime? - Original Message - From: Julian Elischer [EMAIL PROTECTED] To: Darren Pilgrim [EMAIL PROTECTED] Cc: Andrei Cojocaru [EMAIL PROTECTED]; Cy Schubert - CITS Open Systems Group [EMAIL PROTECTED]; [EMAIL PROTECTED] Sent: Wednesday, July 17, 2002 14:50 Subject: Re: Counting the clock cycles depending on the acuracy needed use the uptime.. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
I need a way to properly determine passage of time that is not affected if I change the system clock for example. how about using setitimer(2) - ITIMER_REAL? since it appears(?) on almost all unix(-like) platforms this expires based only on callout (or jiffies) ticks countdown, and settimeofday(2) never seems to bother adjusting callout queues. kenji To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
In message: [EMAIL PROTECTED] Darren Pilgrim [EMAIL PROTECTED] writes: : If you're really worried about it, get a GPS device that can provide : you with a PPS signal for use with ntpd. Then I'd say you could safely : rely on the computer's clock being accurate. If you are lucky enough to find accuracy in the 10s of us close enough. Warner To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
In message: [EMAIL PROTECTED] Poul-Henning Kamp [EMAIL PROTECTED] writes: : In message 005f01c22dd1$7be7d180$0300a8c0@fivehundred, Andrei Cojocaru writ : es: : I am already synchronizing using xntp, that's not the problem. The : problem is by some weird way the clock got out of sync by about 1hr : during daylight switch on one of the computers I run, and I need a : reliable way to get passage of time (I don't need date/time, just : the passage of it) for different internal operations in the program. : : Use UTC time, it has no daylight savings problems. Just stupid leap-seconds :-( Warner To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
M. Warner Losh wrote: In message: [EMAIL PROTECTED] Darren Pilgrim [EMAIL PROTECTED] writes: : If you're really worried about it, get a GPS device that can provide : you with a PPS signal for use with ntpd. Then I'd say you could safely : rely on the computer's clock being accurate. If you are lucky enough to find accuracy in the 10s of us close enough. I don't quite understand what you're saying here. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
In message: [EMAIL PROTECTED] Darren Pilgrim [EMAIL PROTECTED] writes: : M. Warner Losh wrote: : : In message: [EMAIL PROTECTED] : Darren Pilgrim [EMAIL PROTECTED] writes: : : If you're really worried about it, get a GPS device that can provide : : you with a PPS signal for use with ntpd. Then I'd say you could safely : : rely on the computer's clock being accurate. : : If you are lucky enough to find accuracy in the 10s of us close enough. : : I don't quite understand what you're saying here. I'm saying that ntp steers the system clock only +- 40-70us (eg a few 10's of us) in the best client situation on a LAN. Reference clocks can get the system time deviation down to a few microseconds (on the order of 2-5us). phk claims to have gotten better with custom clock hardware... of course these numbers are from FreeBSD 4.3 and the ntp nano-kernel in the kernel has gotten a little better since then. Warner To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Counting the clock cycles
In message [EMAIL PROTECTED], M. Warner Losh writes: In message: [EMAIL PROTECTED] Poul-Henning Kamp [EMAIL PROTECTED] writes: : In message 005f01c22dd1$7be7d180$0300a8c0@fivehundred, Andrei Cojocaru writ : es: : I am already synchronizing using xntp, that's not the problem. The : problem is by some weird way the clock got out of sync by about 1hr : during daylight switch on one of the computers I run, and I need a : reliable way to get passage of time (I don't need date/time, just : the passage of it) for different internal operations in the program. : : Use UTC time, it has no daylight savings problems. Just stupid leap-seconds :-( Well, I have already sent comments to the latest IERS questionaire telling them how ugly we think those are. Unless we want to deal properly with leapseconds and implement TAI, we have no choice in that matter. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
