svn commit: r329013 - head/usr.bin/vmstat

[Justin Hibbits]

Author: jhibbits
Date: Thu Feb  8 05:18:30 2018
New Revision: 329013
URL: https://svnweb.freebsd.org/changeset/base/329013

Log:
  Temporarily widen count for interrupt rate calculations on 32-bit archs
  
  If the interrupt count is very high (greater than ~42M), notably on one-shot
  execution on long running systems, the intermediate multiplication step in the
  rate calculation will overflow the width of a 32-bit architecture long (32
  bits), causing the rest of the calculation to calculate with a truncated value,
  and report very low rates (sometimes 0).
  
  MFC after:	2 weeks

Modified:
  head/usr.bin/vmstat/vmstat.c

Modified: head/usr.bin/vmstat/vmstat.c
==============================================================================
--- head/usr.bin/vmstat/vmstat.c	Thu Feb  8 03:12:25 2018	(r329012)
+++ head/usr.bin/vmstat/vmstat.c	Thu Feb  8 05:18:30 2018	(r329013)
@@ -1304,7 +1304,7 @@ print_intrcnts(unsigned long *intrcnts, unsigned long 
 	for (i = 0, intrcnt=intrcnts, old_intrcnt=old_intrcnts; i < nintr; i++) {
 		if (intrname[0] != '\0' && (*intrcnt != 0 || aflag)) {
 			count = *intrcnt - *old_intrcnt;
-			rate = (count * 1000 + period_ms / 2) / period_ms;
+			rate = ((uint64_t)count * 1000 + period_ms / 2) / period_ms;
 			xo_open_instance("interrupt");
 			xo_emit("{d:name/%-*s}{ket:name/%s} "
 			    "{:total/%20lu} {:rate/%10lu}\n",