Now that we have 64 bit jiffies and also a separate <linux/jiffies.h> in
2.5.18, I think it's time to finally use it to get rid of uptime
wraparounds.
I've put together what I think is minimally needed and commonly
acceptable, i.e. no timer gymnastics etc.:
- use 64 bit jiffies for uptime via sysinfo
- use 64 bit jiffies for uptime via /proc/uptime
- use 64 bit jiffies in the oom_killer
- bump up process start time in task_struct to 64 bits.
This prevents reporting processes as having started in the future
after 32 bit jiffies wrap
- change BSD accounting and /proc/array accordingly
- extend kernel_stat.per_cpu_[user,nice,system] from int to long,
This prevents overflow on 64 bit platforms after about 48 days.
Tim
--- linux-2.5.18/include/linux/jiffies.h Sat May 25 09:35:11 2002
+++ linux-2.5.18-j64/include/linux/jiffies.h Sat May 25 11:20:46 2002
@@ -2,13 +2,32 @@
#define _LINUX_JIFFIES_H
#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <asm/system.h>
/*
* The 64-bit value is not volatile - you MUST NOT read it
- * without holding read_lock_irq(&xtime_lock)
+ * without holding read_lock_irq(&xtime_lock).
+ * get_jiffies64() will do this for you as appropriate.
*/
extern u64 jiffies_64;
extern unsigned long volatile jiffies;
+
+static inline u64 get_jiffies64(void)
+{
+#if BITS_PER_LONG < 64
+ extern rwlock_t xtime_lock;
+ unsigned long flags;
+ u64 tmp;
+
+ read_lock_irqsave(&xtime_lock, flags);
+ tmp = jiffies_64;
+ read_unlock_irqrestore(&xtime_lock, flags);
+ return tmp;
+#else
+ return (u64)jiffies;
+#endif
+}
/*
* These inlines deal with timer wrapping correctly. You are
--- linux-2.5.18/kernel/info.c Tue May 21 07:07:31 2002
+++ linux-2.5.18-j64/kernel/info.c Sat May 25 10:03:52 2002
@@ -12,15 +12,19 @@
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
+#include <asm/div64.h>
asmlinkage long sys_sysinfo(struct sysinfo *info)
{
struct sysinfo val;
+ u64 uptime;
memset((char *)&val, 0, sizeof(struct sysinfo));
cli();
- val.uptime = jiffies / HZ;
+ uptime = get_jiffies64();
+ do_div(uptime, HZ);
+ val.uptime = (unsigned long) uptime;
val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
--- linux-2.5.18/mm/oom_kill.c Tue May 21 07:07:29 2002
+++ linux-2.5.18-j64/mm/oom_kill.c Sat May 25 10:03:52 2002
@@ -69,11 +69,10 @@
/*
* CPU time is in seconds and run time is in minutes. There is no
* particular reason for this other than that it turned out to work
- * very well in practice. This is not safe against jiffie wraps
- * but we don't care _that_ much...
+ * very well in practice.
*/
cpu_time = (p->times.tms_utime + p->times.tms_stime) >> (SHIFT_HZ + 3);
- run_time = (jiffies - p->start_time) >> (SHIFT_HZ + 10);
+ run_time = (get_jiffies64() - p->start_time) >> (SHIFT_HZ + 10);
points /= int_sqrt(cpu_time);
points /= int_sqrt(int_sqrt(run_time));
--- linux-2.5.18/fs/proc/proc_misc.c Sat May 25 09:14:06 2002
+++ linux-2.5.18-j64/fs/proc/proc_misc.c Sat May 25 10:31:04 2002
@@ -36,10 +36,12 @@
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/seq_file.h>
+#include <linux/jiffies.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
+#include <asm/div64.h>
#define LOAD_INT(x) ((x) >> FSHIFT)
@@ -93,34 +95,36 @@
static int uptime_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
- unsigned long uptime;
- unsigned long idle;
+ u64 uptime;
+ unsigned long uptime_remainder;
int len;
- uptime = jiffies;
- idle = init_task.times.tms_utime + init_task.times.tms_stime;
+ uptime = get_jiffies64();
+ uptime_remainder = (unsigned long) do_div(uptime, HZ);
- /* The formula for the fraction parts really is ((t * 100) / HZ) % 100, but
- that would overflow about every five days at HZ == 100.
- Therefore the identity a = (a / b) * b + a % b is used so that it is
- calculated as (((t / HZ) * 100) + ((t % HZ) * 100) / HZ) % 100.
- The part in front of the '+' always evaluates as 0 (mod 100). All divisions
- in the above formulas are truncating. For HZ being a power of 10, the
- calculations simplify to the version in the #else part (if the printf
- format is adapted to the same number of digits as zeroes in HZ.
- */
#if HZ!=100
- len = sprintf(page,"%lu.%02lu %lu.%02lu\n",
- uptime / HZ,
- (((uptime % HZ) * 100) / HZ) % 100,
- idle / HZ,
- (((idle % HZ) * 100) / HZ) % 100);
+ {
+ u64 idle = init_task.times.tms_utime+init_task.times.tms_stime;
+ unsigned long idle_remainder;
+
+ idle_remainder = (unsigned long) do_div(idle, HZ);
+ len = sprintf(page,"%lu.%02lu %lu.%02lu\n",
+ (unsigned long) uptime,
+ (uptime_remainder * 100) / HZ,
+ (unsigned long) idle,
+ (idle_remainder * 100) / HZ);
+ }
#else
- len = sprintf(page,"%lu.%02lu %lu.%02lu\n",
- uptime / HZ,
- uptime % HZ,
- idle / HZ,
- idle % HZ);
+ {
+ unsigned long idle = init_task.times.tms_utime
+ + init_task.times.tms_stime;
+
+ len = sprintf(page,"%lu.%02lu %lu.%02lu\n",
+ (unsigned long) uptime,
+ uptime_remainder,
+ idle / HZ,
+ idle % HZ);
+ }
#endif
return proc_calc_metrics(page, start, off, count, eof, len);
}
@@ -277,8 +281,9 @@
{
int i, len;
extern unsigned long total_forks;
- unsigned long jif = jiffies;
- unsigned int sum = 0, user = 0, nice = 0, system = 0;
+ u64 jif = get_jiffies64();
+ unsigned int sum = 0;
+ unsigned long user = 0, nice = 0, system = 0;
int major, disk;
for (i = 0 ; i < smp_num_cpus; i++) {
@@ -293,17 +298,19 @@
#endif
}
- len = sprintf(page, "cpu %u %u %u %lu\n", user, nice, system,
- jif * smp_num_cpus - (user + nice + system));
+ len = sprintf(page, "cpu %lu %lu %lu %llu\n", user, nice, system,
+ (unsigned long long) jif * smp_num_cpus
+ - user - nice - system);
for (i = 0 ; i < smp_num_cpus; i++)
- len += sprintf(page + len, "cpu%d %u %u %u %lu\n",
+ len += sprintf(page + len, "cpu%d %lu %lu %lu %llu\n",
i,
kstat.per_cpu_user[cpu_logical_map(i)],
kstat.per_cpu_nice[cpu_logical_map(i)],
kstat.per_cpu_system[cpu_logical_map(i)],
- jif - ( kstat.per_cpu_user[cpu_logical_map(i)] \
- + kstat.per_cpu_nice[cpu_logical_map(i)] \
- + kstat.per_cpu_system[cpu_logical_map(i)]));
+ (unsigned long long)
+ jif - kstat.per_cpu_user[cpu_logical_map(i)]
+ - kstat.per_cpu_nice[cpu_logical_map(i)]
+ - kstat.per_cpu_system[cpu_logical_map(i)]);
len += sprintf(page + len,
"page %u %u\n"
"swap %u %u\n"
@@ -339,12 +346,13 @@
}
}
+ do_div(jif, HZ);
len += sprintf(page + len,
"\nctxt %lu\n"
"btime %lu\n"
"processes %lu\n",
nr_context_switches(),
- xtime.tv_sec - jif / HZ,
+ xtime.tv_sec - (unsigned long) jif,
total_forks);
return proc_calc_metrics(page, start, off, count, eof, len);
--- linux-2.5.18/include/linux/sched.h Sat May 25 09:40:07 2002
+++ linux-2.5.18-j64/include/linux/sched.h Sat May 25 11:23:20 2002
@@ -312,7 +312,7 @@
unsigned long it_real_incr, it_prof_incr, it_virt_incr;
struct timer_list real_timer;
struct tms times;
- unsigned long start_time;
+ u64 start_time;
long per_cpu_utime[NR_CPUS], per_cpu_stime[NR_CPUS];
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
unsigned long min_flt, maj_flt, nswap, cmin_flt, cmaj_flt, cnswap;
--- linux-2.5.18/kernel/fork.c Tue May 21 07:07:31 2002
+++ linux-2.5.18-j64/kernel/fork.c Sat May 25 10:04:23 2002
@@ -700,7 +700,7 @@
#endif
p->array = NULL;
p->lock_depth = -1; /* -1 = no lock */
- p->start_time = jiffies;
+ p->start_time = get_jiffies64();
INIT_LIST_HEAD(&p->local_pages);
--- linux-2.5.18/fs/proc/array.c Tue May 21 07:07:30 2002
+++ linux-2.5.18-j64/fs/proc/array.c Sat May 25 10:04:23 2002
@@ -345,7 +345,7 @@
ppid = task->pid ? task->real_parent->pid : 0;
read_unlock(&tasklist_lock);
res = sprintf(buffer,"%d (%s) %c %d %d %d %d %d %lu %lu \
-%lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld %lu %lu %ld %lu %lu %lu %lu %lu \
+%lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld %llu %lu %ld %lu %lu %lu %lu %lu \
%lu %lu %lu %lu %lu %lu %lu %lu %d %d\n",
task->pid,
task->comm,
@@ -368,7 +368,7 @@
nice,
0UL /* removed */,
task->it_real_value,
- task->start_time,
+ (unsigned long long)(task->start_time),
vsize,
mm ? mm->rss : 0, /* you might want to shift this left 3 */
task->rlim[RLIMIT_RSS].rlim_cur,
diff -urP linux-2.5.18/kernel/acct.c linux-2.5.18-j64/kernel/acct.c
--- linux-2.5.18/kernel/acct.c Tue May 21 07:07:40 2002
+++ linux-2.5.18-j64/kernel/acct.c Sat May 25 10:05:00 2002
@@ -50,6 +50,7 @@
#include <linux/file.h>
#include <linux/tty.h>
#include <asm/uaccess.h>
+#include <asm/div64.h>
/*
* These constants control the amount of freespace that suspend and
@@ -299,6 +300,7 @@
mm_segment_t fs;
unsigned long vsize;
unsigned long flim;
+ u64 elapsed;
/*
* First check to see if there is enough free_space to continue
@@ -316,9 +318,11 @@
strncpy(ac.ac_comm, current->comm, ACCT_COMM);
ac.ac_comm[ACCT_COMM - 1] = '\0';
- ac.ac_btime = CT_TO_SECS(current->start_time) +
- (xtime.tv_sec - (jiffies / HZ));
- ac.ac_etime = encode_comp_t(jiffies - current->start_time);
+ elapsed = get_jiffies64() - current->start_time;
+ ac.ac_etime = encode_comp_t(elapsed > (unsigned long) -1l ?
+ (unsigned long) -1l : (unsigned long) elapsed);
+ do_div(elapsed, HZ);
+ ac.ac_btime = xtime.tv_sec - elapsed;
ac.ac_utime = encode_comp_t(current->times.tms_utime);
ac.ac_stime = encode_comp_t(current->times.tms_stime);
ac.ac_uid = current->uid;
--- linux-2.5.18/include/linux/kernel_stat.h Sat May 25 09:40:07 2002
+++ linux-2.5.18-j64/include/linux/kernel_stat.h Sat May 25 11:23:32 2002
@@ -16,9 +16,9 @@
#define DK_MAX_DISK 16
struct kernel_stat {
- unsigned int per_cpu_user[NR_CPUS],
- per_cpu_nice[NR_CPUS],
- per_cpu_system[NR_CPUS];
+ unsigned long per_cpu_user[NR_CPUS],
+ per_cpu_nice[NR_CPUS],
+ per_cpu_system[NR_CPUS];
unsigned int dk_drive[DK_MAX_MAJOR][DK_MAX_DISK];
unsigned int dk_drive_rio[DK_MAX_MAJOR][DK_MAX_DISK];
unsigned int dk_drive_wio[DK_MAX_MAJOR][DK_MAX_DISK];
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri May 31 2002 - 22:00:15 EST