On Tue, 23 Feb 2016 13:49:15 +0100 Peter Zijlstra <[email protected]> wrote:
> On Mon, Feb 22, 2016 at 04:26:53PM -0500, Steven Rostedt wrote: > > From: "Steven Rostedt (Red Hat)" <[email protected]> > > > > To have nanosecond output displayed in a more human readable format, its > > nicer to convert it to a seconds format (XXX.YYYYYYYYY). The problem is that > > to do so, the numbers must be divided by NSEC_PER_SEC, and moded too. But as > > these numbers are 64 bit, this can not be done simply with '/' and '%' > > operators, but must use do_div() instead. > > Would not div_[us]64_rem() make more sense? It would typically result in > just the one division, instead of two. The problem is, how do you do that in a printf() statement? We have "%llu.%09ul" which is two arguments in the printf(). And the values we are processing can't be modified. Which is why the macro uses ({ }) and creates a temp variable. -- Steve
