btreplay: Machines are now large enough that holes need to be dealt with

The current method fails if once we hit the first offlined cpu.  This
will correct that case.  However this still underreports the number cpus if
the last cpu are offlined.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/btreplay/btreplay.c b/btreplay/btreplay.c
index 20494e0d31f1814c1ca45d3816ac76b1cd74663a..6f0ba634024d9f75b54bde8b54e44234a1174a63 100644 (file)
--- a/btreplay/btreplay.c
+++ b/btreplay/btreplay.c
@@ -502,6 +502,7 @@ static inline void start_iter(void)
  */
 static void get_ncpus(void)
 {
+       long last_cpu;
        cpu_set_t cpus;
 
        if (sched_getaffinity(getpid(), sizeof(cpus), &cpus)) {
@@ -509,12 +510,11 @@ static void get_ncpus(void)
                /*NOTREACHED*/
        }
 
-       /*
-        * XXX This assumes (perhaps wrongly) that there are no /holes/ 
-        * XXX in the mask.
-        */
-       for (ncpus = 0; ncpus < CPU_SETSIZE && CPU_ISSET(ncpus, &cpus); ncpus++)
-               ;
+       ncpus = -1;
+       for (last_cpu = 0; last_cpu < CPU_SETSIZE && CPU_ISSET(last_cpu, &cpus); last_cpu++)
+               if (CPU_ISSET( last_cpu, &cpus) ) 
+                       ncpus = last_cpu;
+       ncpus++;
        if (ncpus == 0) {
                fatal(NULL, ERR_SYSCALL, "Insufficient number of CPUs\n");
                /*NOTREACHED*/