On Sun, Jul 21, 2024 at 09:23:46AM +0200, Christophe JAILLET wrote: > 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@xxxxxxxxxx> > --- > This patch is compile tested only. > I introduced a bug in v1 (see 1st item in the changes below), so it should > definitively be tested by someone! > > v1 was un-usable because seq_buf_putc() was not exported. It is now > available since v6.7. > > Because of the changes, I don't know if the previous R-b should kept. > In case, it was: > Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> > Reviewed-by: Davidlohr Bueso <dave@xxxxxxxxxxxx> It would be good for them to take another look. In the meantime: Tested-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > Changes in v2: > - Use seq_buf_printf() alseo for the first string, otherwise it would > get lost > - Use seq_buf_str() instead of seq_buf_terminate() because the API has > changed > > v1: https://lore.kernel.org/all/bbbab32e3e104bdc2238724a6a4a85e539f49ddd.1698512661.git.christophe.jaillet@xxxxxxxxxx/ > --- > kernel/rcu/refscale.c | 25 ++++++++++++++----------- > 1 file changed, 14 insertions(+), 11 deletions(-) > > diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c > index f4ea5b1ec068..cfec0648e141 100644 > --- a/kernel/rcu/refscale.c > +++ b/kernel/rcu/refscale.c > @@ -28,6 +28,7 @@ > #include <linux/rcupdate_trace.h> > #include <linux/reboot.h> > #include <linux/sched.h> > +#include <linux/seq_buf.h> > #include <linux/spinlock.h> > #include <linux/smp.h> > #include <linux/stat.h> > @@ -891,32 +892,34 @@ static u64 process_durations(int n) > { > int i; > struct reader_task *rt; > - char buf1[64]; > + struct seq_buf s; > char *buf; > u64 sum = 0; > > buf = kmalloc(800 + 64, GFP_KERNEL); > if (!buf) > return 0; > - buf[0] = 0; > - sprintf(buf, "Experiment #%d (Format: <THREAD-NUM>:<Total loop time in ns>)", > - exp_idx); > + seq_buf_init(&s, buf, 800 + 64); > + > + 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++) { > rt = &(reader_tasks[i]); > - sprintf(buf1, "%d: %llu\t", i, rt->last_duration_ns); > > if (i % 5 == 0) > - strcat(buf, "\n"); > - if (strlen(buf) >= 800) { > - pr_alert("%s", buf); > - buf[0] = 0; > + seq_buf_putc(&s, '\n'); > + > + if (seq_buf_used(&s) >= 800) { > + 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; > } > - pr_alert("%s\n", buf); > + pr_alert("%s\n", seq_buf_str(&s)); > > kfree(buf); > return sum; > -- > 2.45.2 > >
