[gmpi] Reqs 3.8 Events - abs. vs rel. timestamps
- From: Tim Hockin <thockin@xxxxxxxxxx>
- To: gmpi@xxxxxxxxxxxxx
- Date: Tue, 23 Dec 2003 15:09:08 -0800
Let's see if we can wrap up some of these topics. I know it is Holidays
soon, so if no one replies, I'll understand. But if you can reply, I would
be very happy to put Section 3.8 to bed inside of 2003.
On absolute timestamps vs relative timestamps:
I've been through all the emails, and I find the following to be the core
points.
* We all agree that the master time counter should be 64 bits. Signed or not
doesn't matter much. Assuming 1 MHz sampling rate, we get the following
times until the master counter rolls over:
signed: (2^63)/(10^6)/60/60/24/365.25 = 292271.023 years
unsigned: (2^64)/(10^6)/60/60/24/365.25 = 584542.046 years
* Many people don't care whether we choose 32 bit offsets (from start of
buffer) or 64 bit absolutes for the timestamp on each event. Some people
do care, and all those people have voted for 32 bit offsets.
* Assuming the same 1 MHz sampling rate, we get a maximum time per buffer of:
signed: (2^31)/(10^6)/60 = 35.79 seconds
unsigned: (2^32)/(10^6)/60 = 71.58 seconds
Can we live with a maximum of ~36 - ~72 seconds per buffer max? I don't see
a problem with it that can't be solved relatively easily. :) Signedness
should be left for the spec or the implementation to decide, probably.
Based on this, I'm inclined to believe we have come to decide that event
timestamps are 32 bit offsets from the start of the buffer.
What think?
Tim
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Other related posts:
- » [gmpi] Reqs 3.8 Events - abs. vs rel. timestamps
- » [gmpi] Re: Reqs 3.8 Events - abs. vs rel. timestamps
- [gmpi] Re: Reqs 3.8 Events - abs. vs rel. timestamps
- From: David Olofson
- [gmpi] Re: New Reqs 3.8 - Events
- From: Tim Hockin
- [gmpi] Re: New Reqs 3.8 - Events
- From: Michael Gogins
- [gmpi] Re: New Reqs 3.8 - Events
- From: David Olofson
- [gmpi] Re: New Reqs 3.8 - Events
- From: Chris Grigg
- [gmpi] Re: New Reqs 3.8 - Events
- From: Tim Hockin
- [gmpi] Re: New Reqs 3.8 - Events
- From: Jeff McClintock
- [gmpi] Re: New Reqs 3.8 - Events
- From: Steve Harris
- [gmpi] Re: New Reqs 3.8 - Events
- From: Chris Grigg
- [gmpi] Re: New Reqs 3.8 - Events
- From: Tim Hockin
- [gmpi] Re: New Reqs 3.8 - Events
- From: Steve Harris