lkml.org 
[lkml]   [2012]   [Jun]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [tip:perf/core] perf/x86: Add generic Intel uncore PMU support
On 06/21/2012 03:51 PM, Andrew Morton wrote:
>
> What *is* significant is the effect of a signedness change upon
> arithmetic, conversions, warnings, etc. And whether such a change
> might actually introduce bugs.
>
>
> Back away and ask the broader questions: why did ktime_t choose
> unsigned? Is time a signed concept? What is the right thing to do
> here, from a long-term design perspective?

Time is definitely a signed concept -- it has no beginning or end (well,
the Big Bang, but the ±110 Myr or so uncertainty of the exact timing of
the Big Bang makes it a horridly awkward choice for epoch.)

Now, for some users of time you can inherently guarantee there will
never be any references to time before a particular event, e.g. system
boot, in which case an unsigned number might make sense, but as a whole
I think using a signed type as time_t in nearly all Unix implementation
was The Right Thing.

-hpa
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2012-06-22 01:41    [W:0.123 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site