On Thu 15.May'08 at 1:27:04 +0300, Adrian Bunk wrote: > On Thu, May 08, 2008 at 09:55:27PM -0700, Darrick J. Wong wrote: > > On Thu, May 08, 2008 at 04:34:43PM -0700, Andrew Morton wrote: > > > > > This driver is littered with 64-bit divides and doesn't link on i386. > > > I'll make it depend on CONFIG_64BIT for now. > > > > Oops, sorry, I didn't remember that one can't do 64-bit division on > > i386. The patch below fixes that. > > --- > > ibmaem: Fix 64-bit division on 32-bit platforms > > > > Signed-off-by: Darrick J. Wong <djwong at us.ibm.com> > > --- > > > > drivers/hwmon/ibmaem.c | 6 ++++-- > > 1 files changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c > > index 22fa7d6..f808ca3 100644 > > --- a/drivers/hwmon/ibmaem.c > > +++ b/drivers/hwmon/ibmaem.c > >... > > @@ -864,9 +865,10 @@ static ssize_t aem_show_power(struct device *dev, > >... > > time = timespec_to_ns(&a) - timespec_to_ns(&b); > > - time /= 1000; > > + time = div_u64(time, 1000); > > > > - return sprintf(buf, "%llu\n", (after - before) * 1000000000 / time); > > + return sprintf(buf, "%llu\n", > > + div64_u64((after - before) * 1000000000, time)); > > } > >... > > What are you actually trying to do here? > > Converting mJ/ns to uJ/s? > > Or do you want to convert mJ/ns to Watt in which case you should > multiply "time" with 1000 instead of dividing it through 1000? To avoid these kind of doubts may I suggest using the time conversion definitions of include/linux/time.h? It would be much easier to understand the intention with NSEC_PER_SEC, USEC_PER_SEC etc (comments would also help) > In any case you should only need one expensive 64bit division > and you can fold the operation with 1000 into the second division. I agree.
