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SubjectRe: [Patch] enable uptime display > 497 days
Thank you for doing this labor of love -

I will let you know how it goes sometime
after March 23, 2003 -

cu

jjs

Tim Schmielau wrote:

> Dear Linus,
>
> the appended patch enables 32 bit linux boxes to display more than
> 497.1 days of uptime. No user land application changes are needed.
> This is the solution that came out of the "[Patch] Re: Nasty suprise with
> uptime" thread a week ago.
>
> As no objections have been raised since then, and as I was able to cure
> the observed lockups after jiffies wraparound by the "[Patch] fix
> incorrect jiffies compares" just posted to lkml, I believe this to be
> ready for inclusion into the main tree.
>
> The patch introduces a get_jiffies64() function that internally counts the
> jiffies wrap. This way there is no overhead neither in the timer interrupt
> nor in functions not interested in a 64bit jiffies value. IMHO this patch
> does not interfere with the possible introduction of a "real" 64 bit
> jiffies counter at later times, as the get_jiffies64() can still be
> retained then to provide the necessary locking.
>
> I also extended the start_time field of struct task_struct to 64 bits so
> that ps output will still be ok after the 32 bit wraparound while keeping
> sub-second resolution of runtimes.
>
> Idle time overflow is dealt with in the same way as the jiffies
> wraparound. The CPU time of the idle task will still overflow as it will
> for every other process getting more than 497.1 days of CPU time, but I
> don't want to blow up every time variable. I believe this to be acceptable
> behavior.
>
> The downshot of counting jiffies wraps in get_jiffies64() is that
> overflows get undetected if for more than 497 days
> - /proc/uptime is not read,
> - sysinfo() is not called,
> - and no new processes are started,
> which altogether is rather unlikely.
>
> Correct uptime display after jiffies wrap is of course only useful if
> there are no stability problems after the wrap. To aid in finding out this
> I added a config time option to initialize the jiffies counter to a value
> 5 minutes before wrap. I kindly ask people to turn this on and watch out.
> It did not affect stability for me anymore after the jiffies comparison
> fixed were applied.
>
> Tim
>
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/Documentation/Configure.help linux-2.4.15-pre2-jiffies64/Documentation/Configure.help
> --- linux-2.4.15-pre2/Documentation/Configure.help Sun Nov 11 10:23:36 2001
> +++ linux-2.4.15-pre2-jiffies64/Documentation/Configure.help Sun Nov 11 10:40:13 2001
> @@ -23550,6 +23550,14 @@
> of the BUG call as well as the EIP and oops trace. This aids
> debugging but costs about 70-100K of memory.
>
> +Debug jiffies counter wraparound (DANGEROUS)
> +CONFIG_DEBUG_JIFFIESWRAP
> + Say Y here to initialize the jiffies counter to a value 5 minutes
> + before wraparound. This may make your system UNSTABLE and its
> + only use is to hunt down the causes of this instability.
> + If you don't know what the jiffies counter is or if you want
> + a stable system, say N.
> +
> Include kgdb kernel debugger
> CONFIG_KGDB
> Include in-kernel hooks for kgdb, the Linux kernel source level
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/arm/config.in linux-2.4.15-pre2-jiffies64/arch/arm/config.in
> --- linux-2.4.15-pre2/arch/arm/config.in Sun Nov 11 10:23:36 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/arm/config.in Sun Nov 11 10:40:13 2001
> @@ -601,6 +601,7 @@
> bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
> bool 'Spinlock debugging' CONFIG_DEBUG_SPINLOCK
> dep_bool 'Disable pgtable cache' CONFIG_NO_PGT_CACHE $CONFIG_CPU_26
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> # These options are only for real kernel hackers who want to get their hands dirty.
> dep_bool 'Kernel low-level debugging functions' CONFIG_DEBUG_LL $CONFIG_EXPERIMENTAL
> dep_bool ' Kernel low-level debugging messages via footbridge serial port' CONFIG_DEBUG_DC21285_PORT $CONFIG_DEBUG_LL $CONFIG_FOOTBRIDGE
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/cris/config.in linux-2.4.15-pre2-jiffies64/arch/cris/config.in
> --- linux-2.4.15-pre2/arch/cris/config.in Mon Oct 15 22:42:14 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/cris/config.in Sun Nov 11 10:40:13 2001
> @@ -250,4 +250,5 @@
> if [ "$CONFIG_PROFILE" = "y" ]; then
> int ' Profile shift count' CONFIG_PROFILE_SHIFT 2
> fi
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/i386/config.in linux-2.4.15-pre2-jiffies64/arch/i386/config.in
> --- linux-2.4.15-pre2/arch/i386/config.in Sat Nov 3 02:46:47 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/i386/config.in Sun Nov 11 10:40:13 2001
> @@ -405,6 +405,7 @@
> bool ' Magic SysRq key' CONFIG_MAGIC_SYSRQ
> bool ' Spinlock debugging' CONFIG_DEBUG_SPINLOCK
> bool ' Verbose BUG() reporting (adds 70K)' CONFIG_DEBUG_BUGVERBOSE
> + bool ' Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> fi
>
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/m68k/config.in linux-2.4.15-pre2-jiffies64/arch/m68k/config.in
> --- linux-2.4.15-pre2/arch/m68k/config.in Tue Jun 12 04:15:27 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/m68k/config.in Sun Nov 11 10:40:13 2001
> @@ -545,4 +545,5 @@
>
> #bool 'Debug kmalloc/kfree' CONFIG_DEBUG_MALLOC
> bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/mips/config.in linux-2.4.15-pre2-jiffies64/arch/mips/config.in
> --- linux-2.4.15-pre2/arch/mips/config.in Mon Oct 15 22:41:34 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/mips/config.in Sun Nov 11 10:40:13 2001
> @@ -519,4 +519,5 @@
> if [ "$CONFIG_SMP" != "y" ]; then
> bool 'Run uncached' CONFIG_MIPS_UNCACHED
> fi
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/parisc/config.in linux-2.4.15-pre2-jiffies64/arch/parisc/config.in
> --- linux-2.4.15-pre2/arch/parisc/config.in Wed Apr 18 02:19:25 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/parisc/config.in Sun Nov 11 10:40:13 2001
> @@ -206,5 +206,6 @@
>
> #bool 'Debug kmalloc/kfree' CONFIG_DEBUG_MALLOC
> bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
>
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/ppc/config.in linux-2.4.15-pre2-jiffies64/arch/ppc/config.in
> --- linux-2.4.15-pre2/arch/ppc/config.in Sat Nov 3 02:43:54 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/ppc/config.in Sun Nov 11 10:40:13 2001
> @@ -391,4 +391,5 @@
> bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
> bool 'Include kgdb kernel debugger' CONFIG_KGDB
> bool 'Include xmon kernel debugger' CONFIG_XMON
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/sh/config.in linux-2.4.15-pre2-jiffies64/arch/sh/config.in
> --- linux-2.4.15-pre2/arch/sh/config.in Mon Oct 15 22:36:48 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/sh/config.in Sun Nov 11 10:40:13 2001
> @@ -385,4 +385,5 @@
> if [ "$CONFIG_SH_STANDARD_BIOS" = "y" ]; then
> bool 'Early printk support' CONFIG_SH_EARLY_PRINTK
> fi
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/arch/sparc/config.in linux-2.4.15-pre2-jiffies64/arch/sparc/config.in
> --- linux-2.4.15-pre2/arch/sparc/config.in Tue Jun 12 04:15:27 2001
> +++ linux-2.4.15-pre2-jiffies64/arch/sparc/config.in Sun Nov 11 10:40:13 2001
> @@ -265,4 +265,5 @@
> comment 'Kernel hacking'
>
> bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
> +bool 'Debug jiffies counter wraparound (DANGEROUS)' CONFIG_DEBUG_JIFFIESWRAP
> endmenu
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/fs/proc/array.c linux-2.4.15-pre2-jiffies64/fs/proc/array.c
> --- linux-2.4.15-pre2/fs/proc/array.c Thu Oct 11 18:00:01 2001
> +++ linux-2.4.15-pre2-jiffies64/fs/proc/array.c Sun Nov 11 10:40:13 2001
> @@ -343,7 +343,7 @@
> ppid = task->pid ? task->p_opptr->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,
> @@ -366,7 +366,7 @@
> nice,
> 0UL /* removed */,
> task->it_real_value,
> - task->start_time,
> + (unsigned long long)(task->start_time) - INITIAL_JIFFIES,
> vsize,
> mm ? mm->rss : 0, /* you might want to shift this left 3 */
> task->rlim[RLIMIT_RSS].rlim_cur,
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/fs/proc/proc_misc.c linux-2.4.15-pre2-jiffies64/fs/proc/proc_misc.c
> --- linux-2.4.15-pre2/fs/proc/proc_misc.c Thu Oct 11 19:46:57 2001
> +++ linux-2.4.15-pre2-jiffies64/fs/proc/proc_misc.c Sun Nov 11 10:40:14 2001
> @@ -39,6 +39,7 @@
> #include <asm/uaccess.h>
> #include <asm/pgtable.h>
> #include <asm/io.h>
> +#include <asm/div64.h>
>
> #define LOAD_INT(x) ((x) >> FSHIFT)
> @@ -100,37 +101,59 @@
> return proc_calc_metrics(page, start, off, count, eof, len);
> }
>
> +#if BITS_PER_LONG < 48
> +
> +u64 get_idle64(void)
> +{
> + static unsigned long idle_hi, idle_last;
> + static spinlock_t idle64_lock = SPIN_LOCK_UNLOCKED;
> + unsigned long idle;
> +
> + spin_lock(&idle64_lock);
> + idle = init_tasks[0]->times.tms_utime + init_tasks[0]->times.tms_stime;
> + if (idle < idle_last) /* We have a wrap */
> + idle_hi++;
> + idle_last = idle;
> + spin_unlock(&idle64_lock);
> +
> + return (idle | ((u64)idle_hi) << BITS_PER_LONG);
> +}
> +
> +#else
> + /* Idle time won't overflow for 8716 years at HZ==1024 */
> +
> +static inline u64 get_idle64(void)
> +{
> + return (u64)(init_tasks[0]->times.tms_utime
> + + init_tasks[0]->times.tms_stime);
> +}
> +
> +#endif /* BITS_PER_LONG < 48 */
> +
> 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, idle;
> + unsigned long uptime_remainder, idle_remainder;
> int len;
>
> - uptime = jiffies;
> - idle = init_tasks[0]->times.tms_utime + init_tasks[0]->times.tms_stime;
> + uptime = get_jiffies64() - INITIAL_JIFFIES;
> + uptime_remainder = (unsigned long) do_div(uptime, HZ);
> + idle = get_idle64();
> + idle_remainder = (unsigned long) do_div(idle, 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);
> + (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) uptime,
> + uptime_remainder,
> + (unsigned long) idle,
> + idle_remainder);
> #endif
> return proc_calc_metrics(page, start, off, count, eof, len);
> }
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/include/linux/sched.h linux-2.4.15-pre2-jiffies64/include/linux/sched.h
> --- linux-2.4.15-pre2/include/linux/sched.h Sun Nov 11 10:28:23 2001
> +++ linux-2.4.15-pre2-jiffies64/include/linux/sched.h Sun Nov 11 12:59:22 2001
> @@ -352,7 +352,7 @@
> 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;
> @@ -549,6 +549,8 @@
> #include <asm/current.h>
>
> extern unsigned long volatile jiffies;
> +extern u64 get_jiffies64(void);
> +
> extern unsigned long itimer_ticks;
> extern unsigned long itimer_next;
> extern struct timeval xtime;
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/include/linux/timex.h linux-2.4.15-pre2-jiffies64/include/linux/timex.h
> --- linux-2.4.15-pre2/include/linux/timex.h Mon Nov 5 21:42:13 2001
> +++ linux-2.4.15-pre2-jiffies64/include/linux/timex.h Sun Nov 11 12:54:00 2001
> @@ -53,6 +53,13 @@
>
> #include <asm/param.h>
>
> +#ifdef CONFIG_DEBUG_JIFFIESWRAP
> + /* Make the jiffies counter wrap around sooner. */
> +# define INITIAL_JIFFIES ((unsigned long)(-300*HZ))
> +#else
> +# define INITIAL_JIFFIES 0
> +#endif
> +
> /*
> * The following defines establish the engineering parameters of the PLL
> * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/kernel/acct.c linux-2.4.15-pre2-jiffies64/kernel/acct.c
> --- linux-2.4.15-pre2/kernel/acct.c Mon Mar 19 21:35:08 2001
> +++ linux-2.4.15-pre2-jiffies64/kernel/acct.c Sun Nov 11 10:40:14 2001
> @@ -56,6 +56,7 @@
> #include <linux/tty.h>
>
> #include <asm/uaccess.h>
> +#include <asm/div64.h>
>
> /*
> * These constants control the amount of freespace that suspend and
> @@ -227,20 +228,24 @@
> * This routine has been adopted from the encode_comp_t() function in
> * the kern_acct.c file of the FreeBSD operating system. The encoding
> * is a 13-bit fraction with a 3-bit (base 8) exponent.
> + *
> + * Bumped up to encode 64 bit values. Unfortunately the result may
> + * overflow now.
> */
>
> #define MANTSIZE 13 /* 13 bit mantissa. */
> -#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
> +#define EXPSIZE 3 /* 3 bit exponent. */
> +#define EXPBASE 3 /* Base 8 (3 bit) exponent. */
> #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
>
> -static comp_t encode_comp_t(unsigned long value)
> +static comp_t encode_comp_t(u64 value)
> {
> int exp, rnd;
>
> exp = rnd = 0;
> while (value > MAXFRACT) {
> - rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
> - value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
> + rnd = value & (1 << (EXPBASE - 1)); /* Round up? */
> + value >>= EXPBASE; /* Base 8 exponent == 3 bit shift. */
> exp++;
> }
>
> @@ -248,16 +253,21 @@
> * If we need to round up, do it (and handle overflow correctly).
> */
> if (rnd && (++value > MAXFRACT)) {
> - value >>= EXPSIZE;
> + value >>= EXPBASE;
> exp++;
> }
>
> /*
> * Clean it up and polish it off.
> */
> - exp <<= MANTSIZE; /* Shift the exponent into place */
> - exp += value; /* and add on the mantissa. */
> - return exp;
> + if (exp >= (1 << EXPSIZE)) {
> + /* Overflow. Return largest representable number instead. */
> + return (1ul << (MANTSIZE + EXPSIZE)) - 1;
> + } else {
> + exp <<= MANTSIZE; /* Shift the exponent into place */
> + exp += value; /* and add on the mantissa. */
> + return exp;
> + }
> }
>
> /*
> @@ -277,6 +287,7 @@
> struct acct ac;
> mm_segment_t fs;
> unsigned long vsize;
> + u64 elapsed;
>
> /*
> * First check to see if there is enough free_space to continue
> @@ -294,8 +305,10 @@
> 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);
> + 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;
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/kernel/fork.c linux-2.4.15-pre2-jiffies64/kernel/fork.c
> --- linux-2.4.15-pre2/kernel/fork.c Wed Oct 24 02:44:15 2001
> +++ linux-2.4.15-pre2-jiffies64/kernel/fork.c Sun Nov 11 10:40:14 2001
> @@ -647,7 +647,7 @@
> }
> #endif
> p->lock_depth = -1; /* -1 = no lock */
> - p->start_time = jiffies;
> + p->start_time = get_jiffies64();
>
> INIT_LIST_HEAD(&p->local_pages);
>
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/kernel/info.c linux-2.4.15-pre2-jiffies64/kernel/info.c
> --- linux-2.4.15-pre2/kernel/info.c Sat Apr 21 01:15:40 2001
> +++ linux-2.4.15-pre2-jiffies64/kernel/info.c Sun Nov 11 10:40:14 2001
> @@ -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() - INITIAL_JIFFIES;
> + 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);
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/kernel/timer.c linux-2.4.15-pre2-jiffies64/kernel/timer.c
> --- linux-2.4.15-pre2/kernel/timer.c Mon Oct 8 19:41:41 2001
> +++ linux-2.4.15-pre2-jiffies64/kernel/timer.c Sun Nov 11 13:05:25 2001
> @@ -65,7 +65,7 @@
>
> extern int do_setitimer(int, struct itimerval *, struct itimerval *);
>
> -unsigned long volatile jiffies;
> +unsigned long volatile jiffies = INITIAL_JIFFIES;
>
> unsigned int * prof_buffer;
> unsigned long prof_len;
> @@ -115,9 +115,17 @@
> }
> for (i = 0; i < TVR_SIZE; i++)
> INIT_LIST_HEAD(tv1.vec + i);
> +
> +#if CONFIG_DEBUG_JIFFIESWRAP
> + tv1.index = INITIAL_JIFFIES & TVR_MASK;
> + tv2.index = (INITIAL_JIFFIES >> TVR_BITS) & TVN_MASK;
> + tv3.index = (INITIAL_JIFFIES >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
> + tv4.index = (INITIAL_JIFFIES >> (TVR_BITS + 2*TVN_BITS)) & TVN_MASK;
> + tv5.index = (INITIAL_JIFFIES >> (TVR_BITS + 3*TVN_BITS)) & TVN_MASK;
> +#endif
> }
>
> -static unsigned long timer_jiffies;
> +static unsigned long timer_jiffies = INITIAL_JIFFIES;
>
> static inline void internal_add_timer(struct timer_list *timer)
> {
> @@ -638,7 +646,7 @@
> }
>
> /* jiffies at the most recent update of wall time */
> -unsigned long wall_jiffies;
> +unsigned long wall_jiffies = INITIAL_JIFFIES;
>
> /*
> * This spinlock protect us from races in SMP while playing with xtime. -arca
> @@ -683,6 +691,37 @@
> if (TQ_ACTIVE(tq_timer))
> mark_bh(TQUEUE_BH);
> }
> +
> +
> +#if BITS_PER_LONG < 48
> +
> +u64 get_jiffies64(void)
> +{
> + static unsigned long jiffies_hi = 0;
> + static unsigned long jiffies_last = INITIAL_JIFFIES;
> + static spinlock_t jiffies64_lock = SPIN_LOCK_UNLOCKED;
> + unsigned long jiffies_tmp;
> +
> + spin_lock(&jiffies64_lock);
> + jiffies_tmp = jiffies; /* avoid races */
> + if (jiffies_tmp < jiffies_last) /* We have a wrap */
> + jiffies_hi++;
> + jiffies_last = jiffies_tmp;
> + spin_unlock(&jiffies64_lock);
> +
> + return (jiffies_tmp | ((u64)jiffies_hi) << BITS_PER_LONG);
> +}
> +
> +#else
> + /* jiffies is wide enough to not wrap for 8716 years at HZ==1024 */
> +
> +static inline u64 get_jiffies64(void)
> +{
> + return (u64)jiffies;
> +}
> +
> +#endif /* BITS_PER_LONG < 48 */
> +
>
> #if !defined(__alpha__) && !defined(__ia64__)
>
> diff -u -r --exclude-from dontdiff linux-2.4.15-pre2/mm/oom_kill.c linux-2.4.15-pre2-jiffies64/mm/oom_kill.c
> --- linux-2.4.15-pre2/mm/oom_kill.c Sun Nov 4 02:05:25 2001
> +++ linux-2.4.15-pre2-jiffies64/mm/oom_kill.c Sun Nov 11 10:42:26 2001
> @@ -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));
>
> -
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