on 2021/10/23 7:15, Paul E. McKenney wrote:
On Fri, Oct 22, 2021 at 06:51:11PM +0800, Li Zhijian wrote:
0Day/LKP observed that the refscale results become incompleted
when a larger nruns(such as 300) is specified.
It seems that printk() can accept < 1024 buffer at once.
Print the buffer if its length exceeds 800 simply.
CC: Philip Li <philip.li@xxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxxxxx>
Good catch! A couple of questions below.
Thanx, Paul
---
kernel/rcu/refscale.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 2cbe2a2ba387..b1b9052010fd 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -604,7 +604,7 @@ static u64 process_durations(int n)
char *buf;
u64 sum = 0;
- buf = kmalloc(128 + nreaders * 32, GFP_KERNEL);
+ buf = kmalloc(64 * 20, GFP_KERNEL);
This allocation (and the one below) is 1280 bytes rather than
1024 bytes. Why the extra couple hundred bytes?
Nothing special, so let's change 1024 or (800 + 64 ),which is sufficent as well ?
if (!buf)
return 0;
buf[0] = 0;
@@ -617,13 +617,15 @@ static u64 process_durations(int n)
if (i % 5 == 0)
strcat(buf, "\n");
+ if (strlen(buf) > 800) {
+ pr_alert("%s", buf);
Does the tools/testing/selftests/rcutorture/bin/kvm-recheck-refscale.sh
script also require changes to handle the partial lines?
I missed that, i will take a look at it
Thanks
Zhijian
Same for the later comparison against 800.
+ buf[0] = 0;
+ }
strcat(buf, buf1);
sum += rt->last_duration_ns;
}
- strcat(buf, "\n");
-
- SCALEOUT("%s\n", buf);
+ pr_alert("%s\n", buf);
kfree(buf);
return sum;
@@ -648,7 +650,7 @@ static int main_func(void *arg)
VERBOSE_SCALEOUT("main_func task started");
result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL);
- buf = kzalloc(64 + nruns * 32, GFP_KERNEL);
+ buf = kzalloc(64 * 20, GFP_KERNEL);
if (!result_avg || !buf) {
VERBOSE_SCALEOUT_ERRSTRING("out of memory");
errexit = true;
@@ -701,10 +703,7 @@ static int main_func(void *arg)
if (errexit)
goto err;
- buf[0] = 0;
- strcat(buf, "\n");
- strcat(buf, "Runs\tTime(ns)\n");
-
+ pr_alert("Runs\tTime(ns)\n");
for (exp = 0; exp < nruns; exp++) {
u64 avg;
u32 rem;
@@ -712,9 +711,13 @@ static int main_func(void *arg)
avg = div_u64_rem(result_avg[exp], 1000, &rem);
sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
strcat(buf, buf1);
+ if (strlen(buf) > 800) {
+ pr_alert("%s", buf);
+ buf[0] = 0;
+ }
}
- SCALEOUT("%s", buf);
+ pr_alert("%s", buf);
err:
// This will shutdown everything including us.
--
2.33.0
