Re: [PATCH] Since we have counters in __u64 format we have to print them with %llu macros.

Mikael Pettersson
2007-09-26T12:43:43Z

On Wed, 26 Sep 2007 17:18:06 +0530, Balbir Singh wrote:
> Andreas Schwab wrote:
> > Maxim Uvarov <muvarov@ru.mvista.com> writes:
> >
> >> diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c
> >> index cbee3a2..73924df 100644
> >> --- a/Documentation/accounting/getdelays.c
> >> +++ b/Documentation/accounting/getdelays.c
> >> @@ -208,7 +208,7 @@ void print_delayacct(struct taskstats *t)
> >> void task_context_switch_counts(struct taskstats *t)
> >> {
> >> printf("\n\nTask %15s%15s\n"
> >> - " %15lu%15lu\n",
> >> + " %15llu%15llu\n",
> >> "voluntary", "nonvoluntary",
> >> t->nvcsw, t->nivcsw);
> >
> > __u64 is not always long long.
>
> What is the maximum size of long long across all architectures?
> How does one format __u64 for printing?

With %lu you get warnings when u64 is long long (32-bit).
With %llu you get warnings when u64 is plain long (most 64-bit).

Hence %llu + long long cast, i.e.:
printf("%llu", (unsigned long long)value);

This is ugly but luckily imposes no runtime overheads on
current 32- or 64-bit machines.

This could be done more cleanly if the u64 typedef also
#define:d a corresponding FMT_U64 format string.