nmeter: improve %T fractionals display

function                                             old     new   delta
nmeter_main                                          751     786     +35

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/procps/nmeter.c b/procps/nmeter.c
index e52c868df..4197174ba 100644
--- a/procps/nmeter.c
+++ b/procps/nmeter.c
@@ -985,6 +985,15 @@ int nmeter_main(int argc UNUSED_PARAM, char **argv)
 
         xgettimeofday(&G.start);
         G.tv = G.start;
+
+        // Move back start of monotonic time a bit, to syncronize fractionals of %T and %t:
+        // nmeter -d500 '%6T %6t'
+        // 00:00:00.000161 12:32:07.500161
+        // 00:00:00.500282 12:32:08.000282
+        // 00:00:01.000286 12:32:08.500286
+        if (G.delta > 0)
+                G.start.tv_usec -= (G.start.tv_usec % (unsigned)G.delta);
+
         while (1) {
                 collect_info(first);
                 put_c(G.final_char);
@@ -999,6 +1008,15 @@ int nmeter_main(int argc UNUSED_PARAM, char **argv)
                         int rem;
                         // can be commented out, will sacrifice sleep time precision a bit
                         xgettimeofday(&G.tv);
+
+        // TODO: nmeter -d10000 '%6T %6t'
+        // 00:00:00.770333 12:34:44.770333
+        // 00:00:06.000088 12:34:50.000088
+        // 00:00:16.000094 12:35:00.000094
+        // 00:00:26.000275 12:35:10.000275
+        // we can't syncronize interval to start close to 10 seconds for both
+        // %T and %t (as shown above), but what if there is only %T
+        // in format string? Maybe sync _it_ instead of %t in this case?
                         if (need_seconds)
                                 rem = G.delta - ((ullong)G.tv.tv_sec*1000000 + G.tv.tv_usec) % G.deltanz;
                         else