On Fri, 2006-05-05 at 00:14 +0530, Balbir Singh wrote:
> #else
> static inline void delayacct_set_flag(int flag)
> {}
Please make this
static inline void delayacct_set_flag(int flag) { }
Same in all other files
> @@ -89,6 +99,9 @@ static inline void delayacct_blkio_start
> {}
> static inline void delayacct_blkio_end(void)
> {}
> +static inline int delayacct_add_tsk(struct taskstats *d,
> + struct task_struct *tsk)
> +{ return 0; }
{
return 0;
}
> + *
> + * xxx_count is the number of delay values recorded
> + * xxx_delay_total is the corresponding cumulative delay in nanoseconds
> + *
> + * xxx_delay_total wraps around to zero on overflow
> + * xxx_count incremented regardless of overflow
> + */
Please use a structure for that.
struct delay_account {
ktime_t delay;
u64 count;
};
Also instead of having tons of fields added, please use something like
enum {
CPU_ACCT,
BLKIO_ACCT,
....,
MAX_ACCT_TYPES
};
struct delay_account stats[MAX_ACCT_TYPES];
> + /* Delay waiting for cpu, while runnable
> + * count, delay_total NOT updated atomically
> + */
> + __u64 cpu_count;
> + __u64 cpu_delay_total;
> + /* Following four fields atomically updated using task->delays->lock */
> +
> + /* Delay waiting for synchronous block I/O to complete
> + * does not account for delays in I/O submission
> + */
> + __u64 blkio_count;
> + __u64 blkio_delay_total;
> +
> + /* Delay waiting for page fault I/O (swap in only) */
> + __u64 swapin_count;
> + __u64 swapin_delay_total;
> +
> + /* cpu "wall-clock" running time
> + * On some architectures, value will adjust for cpu time stolen
> + * from the kernel in involuntary waits due to virtualization.
> + * Value is cumulative, in nanoseconds, without a corresponding count
> + * and wraps around to zero silently on overflow
When will this overflow happen ? 2^64 nsec ~= 584 years
> +int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
> +{
Please add some comment what this code does.
> + s64 tmp;
> + struct timespec ts;
> + unsigned long t1,t2,t3;
> +
> + tmp = (s64)d->cpu_run_real_total;
> + tmp += (u64)(tsk->utime + tsk->stime) * TICK_NSEC;
> + d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
> +
> + /*
> + * No locking available for sched_info (and too expensive to add one)
> + * Mitigate by taking snapshot of values
> + */
> + t1 = tsk->sched_info.pcnt;
> + t2 = tsk->sched_info.run_delay;
> + t3 = tsk->sched_info.cpu_time;
> +
> + d->cpu_count += t1;
> +
> + jiffies_to_timespec(t2, &ts);
> + tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts);
> + d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
> +
> + tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000;
> + d->cpu_run_virtual_total =
> + (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
> +
> + /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
> +
> + spin_lock(&tsk->delays->lock);
> + tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
> + d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
I really do not get whatfor all these comparisons are. How can those
values get > 2^63 within a reasonable timeframe ?
> + tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
> + d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
> + d->blkio_count += tsk->delays->blkio_count;
> + d->swapin_count += tsk->delays->swapin_count;
> + spin_unlock(&tsk->delays->lock);
> + return 0;
> +}
> diff -puN kernel/taskstats.c~delayacct-taskstats kernel/taskstats.c
> --- linux-2.6.17-rc3/kernel/taskstats.c~delayacct-taskstats 2006-05-04 09:31:59.000000000 +0530
> +++ linux-2.6.17-rc3-balbir/kernel/taskstats.c 2006-05-04 11:27:53.000000000 +0530
> @@ -18,6 +18,7 @@
>
> #include <linux/kernel.h>
> #include <linux/taskstats_kern.h>
> +#include <linux/delayacct.h>
> #include <net/genetlink.h>
> #include <asm/atomic.h>
>
> @@ -120,7 +121,10 @@ static int fill_pid(pid_t pid, struct ta
> * goto err;
> */
>
> -err:
> + rc = delayacct_add_tsk(stats, tsk);
> + stats->version = TASKSTATS_VERSION;
> +
> + /* Define err: label here if needed */
Please remove that comment. The err label goes to a place where it makes
sense.
> put_task_struct(tsk);
> return rc;
>
> @@ -152,8 +156,14 @@ static int fill_tgid(pid_t tgid, struct
> * break;
> */
>
> + rc = delayacct_add_tsk(stats, tsk);
> + if (rc)
> + break;
> +
> } while_each_thread(first, tsk);
> read_unlock(&tasklist_lock);
> + stats->version = TASKSTATS_VERSION;
> +
>
> /*
> * Accounting subsytems can also add calls here if they don't
> _
> -
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