Re: jiffies_64 vs. jiffies

[Paul Mackerras <paulus@samba.org>]

Atsushi Nemoto writes:

> Hi.  I noticed that the 'jiffies' variable has 'wall_jiffies + 1'
> value in most of time.  I'm using MIPS platform but I think this is
> same for other platforms.
> 
> I suppose this is due to gcc does not know that jiffies_64 and jiffies
> share same place.

I can confirm that the same thing happens on powerpc, both 32-bit and
64-bit.  The compiler loads up jiffies, jiffies_64 and wall_jiffies
into registers before storing back the incremented value into
jiffies_64 and then updating wall_jiffies.

Thanks for finding that, it explains some other strange things that I
have seen happen.

Paul.