Messages in this thread Patch in this message | | | Subject | Re: [updated] [Patch 6/8] delay accounting usage of taskstats interface | From | Thomas Gleixner <> | Date | Tue, 09 May 2006 11:46:48 +0000 |
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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 > _ > - > 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/
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