Re: [RFC/PATCH v4 1/3] add high resolution timer function to debug performance issues

[Karsten Blees <karsten.blees@gmail.com>]

Am 22.05.2014 00:14, schrieb Richard Hansen:
> On 2014-05-20 15:11, Karsten Blees wrote:
>> Add a getnanotime() function that returns nanoseconds since 01/01/1970 as
>> unsigned 64-bit integer (i.e. overflows in july 2554).
> 
> Must it be relative to epoch?  If it was relative to system boot (like
> the NetBSD kernel's nanouptime() function), then you wouldn't have to
> worry about clock adjustments messing with performance stats and you
> might have more options for implementing getnanotime() on various platforms.
> 
> -Richard
> 

Normalizing to the epoch adds the ability to use the same timestamps (div 10e9) in other time-related functions (e.g. gmtime, ctime etc.), with very little overhead (one 64-bit integer addition per call).

The getnanotime() implementation is actually platform independent and can be backed by any time source that returns nanoseconds relative to anything. Getnanotime() is synced to the system clock only once on startup, so if your time source is monotonic (which I think NetBSD's nanouptime() is), you don't have to worry about clock adjustments.

-- 
-- 
*** Please reply-to-all at all times ***
*** (do not pretend to know who is subscribed and who is not) ***
*** Please avoid top-posting. ***
The msysGit Wiki is here: https://github.com/msysgit/msysgit/wiki - Github accounts are free.

You received this message because you are subscribed to the Google
Groups "msysGit" group.
To post to this group, send email to msysgit@googlegroups.com
To unsubscribe from this group, send email to
msysgit+unsubscribe@googlegroups.com
For more options, and view previous threads, visit this group at
http://groups.google.com/group/msysgit?hl=en_US?hl=en

--- 
You received this message because you are subscribed to the Google Groups "msysGit" group.
To unsubscribe from this group and stop receiving emails from it, send an email to msysgit+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.