[PATCH tip/core/rcu 23/30] refperf: Work around 64-bit division

paulmck
2020-06-23T00:31:17Z

From: Arnd Bergmann <arnd@arndb.de>

A 64-bit division was introduced in refperf, breaking compilation
on all 32-bit architectures:

kernel/rcu/refperf.o: in function `main_func':
refperf.c:(.text+0x57c): undefined reference to `__aeabi_uldivmod'

Fix this by using div_u64 to mark the expensive operation.

[ paulmck: Update primitive and format per Nathan Chancellor. ]
Fixes: bd5b16d6c88d ("refperf: Allow decimal nanoseconds")
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Valdis Klētnieks <valdis.kletnieks@vt.edu>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/refperf.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 063eeb0..80d4490 100644
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -478,7 +478,7 @@ static int main_func(void *arg)
if (torture_must_stop())
goto end;

- result_avg[exp] = 1000 * process_durations(nreaders) / (nreaders * loops);
+ result_avg[exp] = div_u64(1000 * process_durations(nreaders), nreaders * loops);
}

// Print the average of all experiments
@@ -489,9 +489,13 @@ static int main_func(void *arg)
strcat(buf, "Runs\tTime(ns)\n");

for (exp = 0; exp < nruns; exp++) {
+ u64 avg;
+ u32 rem;
+
if (errexit)
break;
- sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, result_avg[exp] / 1000, (int)(result_avg[exp] % 1000));
+ avg = div_u64_rem(result_avg[exp], 1000, &rem);
+ sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
strcat(buf, buf1);
}

--
2.9.5