From: Marcelo Tosatti <mtosatti@redhat.com>
To: linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Chuck Newman <chuck.newman@hpe.com>, John Kacur <jkacur@redhat.com>
Subject: [PATCH] rt-tests: oslat: convert to nanoseconds correctly
Date: Thu, 1 Feb 2024 14:50:54 -0300 [thread overview]
Message-ID: <ZbvZ/l9zKjU8Frvy@tpad> (raw)
With buckets of size 1us, accounting for measurements in the
[1ns, 999ns] range are done to the 2us bucket (while they
should be accounted in the 1us bucket):
001 (us): 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
002 (us): 41916187 41937649 41938461 42029055 ...
003 (us): 969 985 958 972 964 986 970 961 973 ...
Fix this by doing a plain cycles -> nanoseconds convertion:
001 (us): 43287555 43086678 43087427 43109974 ...
002 (us): 983 987 985 975 982 960 993 961 992 ...
003 (us): 9 6 7 13 9 22 3 21 3 3 8 8 10 11 3 55
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Reported-by: Chuck Newman <chuck.newman@hpe.com>
diff --git a/src/oslat/oslat.c b/src/oslat/oslat.c
index 4bdca64..13e887d 100644
--- a/src/oslat/oslat.c
+++ b/src/oslat/oslat.c
@@ -334,7 +334,7 @@ static void insert_bucket(struct thread *t, stamp_t value)
uint64_t extra;
double us;
- lat = (value * g.unit_per_us + t->counter_mhz - 1) / t->counter_mhz;
+ lat = (value * g.unit_per_us) / t->counter_mhz;
us = (double)lat / g.unit_per_us;
if (!g.preheat && g.trace_threshold && us >= g.trace_threshold) {
char *line = "%s: Trace threshold (%d us) triggered on cpu %d with %.*f us!\n";
next reply other threads:[~2024-02-01 17:51 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-01 17:50 Marcelo Tosatti [this message]
2024-02-02 16:34 ` [PATCH] rt-tests: oslat: convert to nanoseconds correctly John Kacur
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