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refscale: Optimize process_durations()

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process_durations() is not a hot path, but there is no good reason to
iterate over and over the data already in 'buf'.

Using a seq_buf saves some useless strcat() and the need of a temp buffer.
Data is written directly at the correct place.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Tested-by: "Paul E. McKenney" <paulmck@kernel.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
This commit is contained in:
Christophe JAILLET 2024-07-21 09:23:46 +02:00 committed by Neeraj Upadhyay
parent 3e49aea71d
commit 4e39bb49c2
1 changed files with 14 additions and 11 deletions
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25
kernel/rcu/refscale.c
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@ -28,6 +28,7 @@
#include <linux/rcupdate_trace.h> #include <linux/rcupdate_trace.h>
#include <linux/reboot.h> #include <linux/reboot.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/seq_buf.h>
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/smp.h> #include <linux/smp.h>
#include <linux/stat.h> #include <linux/stat.h>
@ -891,32 +892,34 @@ static u64 process_durations(int n)
{ {
int i; int i;
struct reader_task *rt; struct reader_task *rt;
char buf1[64]; struct seq_buf s;
char *buf; char *buf;
u64 sum = 0; u64 sum = 0;
buf = kmalloc(800 + 64, GFP_KERNEL); buf = kmalloc(800 + 64, GFP_KERNEL);
if (!buf) if (!buf)
return 0; return 0;
buf[0] = 0; seq_buf_init(&s, buf, 800 + 64);
sprintf(buf, "Experiment #%d (Format: <THREAD-NUM>:<Total loop time in ns>)",
exp_idx); seq_buf_printf(&s, "Experiment #%d (Format: <THREAD-NUM>:<Total loop time in ns>)",
exp_idx);
for (i = 0; i < n && !torture_must_stop(); i++) { for (i = 0; i < n && !torture_must_stop(); i++) {
rt = &(reader_tasks[i]); rt = &(reader_tasks[i]);
sprintf(buf1, "%d: %llu\t", i, rt->last_duration_ns);
if (i % 5 == 0) if (i % 5 == 0)
strcat(buf, "\n"); seq_buf_putc(&s, '\n');
if (strlen(buf) >= 800) {
pr_alert("%s", buf); if (seq_buf_used(&s) >= 800) {
buf[0] = 0; pr_alert("%s", seq_buf_str(&s));
seq_buf_clear(&s);
} }
strcat(buf, buf1);
seq_buf_printf(&s, "%d: %llu\t", i, rt->last_duration_ns);
sum += rt->last_duration_ns; sum += rt->last_duration_ns;
} }
pr_alert("%s\n", buf); pr_alert("%s\n", seq_buf_str(&s));
kfree(buf); kfree(buf);
return sum; return sum;