Messages in this thread Patch in this message | | | Subject | [BUGFIX - #764] linux-2.5.70_btime-fix_A1 | From | john stultz <> | Date | 05 Jun 2003 15:14:10 -0700 |
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Andrew, All, Due to a math error in the calculation of /proc/stat's btime, the value could wobble, varying by a single second. The patch fixes this wobble described in bugme bug #764.
Reportedly Hans is seeing larger then 1 second wobbles which I have not been able to reproduce, but that looks to be a separate issue to this math bug.
Please consider for inclusion.
thanks -john
diff -Nru a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c --- a/fs/proc/proc_misc.c Thu Jun 5 15:07:14 2003 +++ b/fs/proc/proc_misc.c Thu Jun 5 15:07:14 2003 @@ -378,8 +378,23 @@ { int i, len; extern unsigned long total_forks; - u64 jif = get_jiffies_64() - INITIAL_JIFFIES; + u64 jif; unsigned int sum = 0, user = 0, nice = 0, system = 0, idle = 0, iowait = 0; + struct timeval now; + unsigned long seq; + + /* Atomically read jiffies and time of day */ + do { + seq = read_seqbegin(&xtime_lock); + + jif = get_jiffies_64(); + do_gettimeofday(&now); + } while (read_seqretry(&xtime_lock, seq)); + + /* calc # of seconds since boot time */ + jif -= INITIAL_JIFFIES; + jif = ((u64)now.tv_sec * HZ) + (now.tv_usec/(1000000/HZ)) - jif; + do_div(jif, HZ); for (i = 0 ; i < NR_CPUS; i++) { int j; @@ -419,7 +434,6 @@ len += sprintf(page + len, " %u", kstat_irqs(i)); #endif - do_div(jif, HZ); len += sprintf(page + len, "\nctxt %lu\n" "btime %lu\n" @@ -427,7 +441,7 @@ "procs_running %lu\n" "procs_blocked %lu\n", nr_context_switches(), - xtime.tv_sec - (unsigned long) jif, + (unsigned long)jif, total_forks, nr_running(), nr_iowait());
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