[RFC] CPU: New state for iopoll
Zhang, Yuan
yuan.zhang at intel.com
Wed Dec 30 16:38:09 PST 2015
This is really goods do helpful, thanks Keith
Sent from my iPhone
> On Dec 30, 2015, at 4:02 PM, Keith Busch <keith.busch at intel.com> wrote:
>
> This accounts for CPU time spent polling for IO seperately from system
> time.
>
> Signed-off-by: Keith Busch <keith.busch at intel.com>
> ---
> block/blk-core.c | 7 ++++++-
> fs/proc/stat.c | 8 ++++++--
> include/linux/kernel_stat.h | 1 +
> include/linux/sched.h | 1 +
> kernel/sched/cpuacct.c | 1 +
> kernel/sched/cputime.c | 7 ++++++-
> 6 files changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 93810f2..b46fc2c 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -3330,6 +3330,7 @@ bool blk_poll(struct request_queue *q, blk_qc_t cookie)
> if (plug)
> blk_flush_plug_list(plug, false);
>
> + current->in_iopoll = 1;
> state = current->state;
> while (!need_resched()) {
> unsigned int queue_num = blk_qc_t_to_queue_num(cookie);
> @@ -3342,19 +3343,23 @@ bool blk_poll(struct request_queue *q, blk_qc_t cookie)
> if (ret > 0) {
> hctx->poll_success++;
> set_current_state(TASK_RUNNING);
> + current->in_iopoll = 0;
> return true;
> }
>
> if (signal_pending_state(state, current))
> set_current_state(TASK_RUNNING);
>
> - if (current->state == TASK_RUNNING)
> + if (current->state == TASK_RUNNING) {
> + current->in_iopoll = 0;
> return true;
> + }
> if (ret < 0)
> break;
> cpu_relax();
> }
>
> + current->in_iopoll = 0;
> return false;
> }
>
> diff --git a/fs/proc/stat.c b/fs/proc/stat.c
> index 510413eb..5982efc 100644
> --- a/fs/proc/stat.c
> +++ b/fs/proc/stat.c
> @@ -81,14 +81,14 @@ static int show_stat(struct seq_file *p, void *v)
> {
> int i, j;
> unsigned long jif;
> - u64 user, nice, system, idle, iowait, irq, softirq, steal;
> + u64 user, nice, system, idle, iowait, iopoll, irq, softirq, steal;
> u64 guest, guest_nice;
> u64 sum = 0;
> u64 sum_softirq = 0;
> unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
> struct timespec boottime;
>
> - user = nice = system = idle = iowait =
> + user = nice = system = idle = iowait = iopoll =
> irq = softirq = steal = 0;
> guest = guest_nice = 0;
> getboottime(&boottime);
> @@ -98,6 +98,7 @@ static int show_stat(struct seq_file *p, void *v)
> user += kcpustat_cpu(i).cpustat[CPUTIME_USER];
> nice += kcpustat_cpu(i).cpustat[CPUTIME_NICE];
> system += kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
> + iopoll += kcpustat_cpu(i).cpustat[CPUTIME_IOPOLL];
> idle += get_idle_time(i);
> iowait += get_iowait_time(i);
> irq += kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
> @@ -128,6 +129,7 @@ static int show_stat(struct seq_file *p, void *v)
> seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(steal));
> seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest));
> seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest_nice));
> + seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(iopoll));
> seq_putc(p, '\n');
>
> for_each_online_cpu(i) {
> @@ -135,6 +137,7 @@ static int show_stat(struct seq_file *p, void *v)
> user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
> nice = kcpustat_cpu(i).cpustat[CPUTIME_NICE];
> system = kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
> + iopoll = kcpustat_cpu(i).cpustat[CPUTIME_IOPOLL];
> idle = get_idle_time(i);
> iowait = get_iowait_time(i);
> irq = kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
> @@ -153,6 +156,7 @@ static int show_stat(struct seq_file *p, void *v)
> seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(steal));
> seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest));
> seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest_nice));
> + seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(iopoll));
> seq_putc(p, '\n');
> }
> seq_printf(p, "intr %llu", (unsigned long long)sum);
> diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
> index 25a822f..c092745 100644
> --- a/include/linux/kernel_stat.h
> +++ b/include/linux/kernel_stat.h
> @@ -28,6 +28,7 @@ enum cpu_usage_stat {
> CPUTIME_STEAL,
> CPUTIME_GUEST,
> CPUTIME_GUEST_NICE,
> + CPUTIME_IOPOLL,
> NR_STATS,
> };
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index edad7a4..b34830e 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1458,6 +1458,7 @@ struct task_struct {
> unsigned in_execve:1; /* Tell the LSMs that the process is doing an
> * execve */
> unsigned in_iowait:1;
> + unsigned in_iopoll:1;
>
> /* Revert to default priority/policy when forking */
> unsigned sched_reset_on_fork:1;
> diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
> index dd7cbb5..5ad3ad4 100644
> --- a/kernel/sched/cpuacct.c
> +++ b/kernel/sched/cpuacct.c
> @@ -200,6 +200,7 @@ static int cpuacct_stats_show(struct seq_file *sf, void *v)
> for_each_online_cpu(cpu) {
> struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
> val += kcpustat->cpustat[CPUTIME_SYSTEM];
> + val += kcpustat->cpustat[CPUTIME_IOPOLL];
> val += kcpustat->cpustat[CPUTIME_IRQ];
> val += kcpustat->cpustat[CPUTIME_SOFTIRQ];
> }
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 05de80b..887c1a9 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -222,6 +222,8 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
> index = CPUTIME_IRQ;
> else if (in_serving_softirq())
> index = CPUTIME_SOFTIRQ;
> + else if (p->in_iopoll)
> + index = CPUTIME_IOPOLL;
> else
> index = CPUTIME_SYSTEM;
>
> @@ -367,7 +369,10 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
> } else if (p->flags & PF_VCPU) { /* System time or guest time */
> account_guest_time(p, cputime, scaled);
> } else {
> - __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
> + if (p->in_iopoll)
> + __account_system_time(p, cputime, scaled, CPUTIME_IOPOLL);
> + else
> + __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
> }
> }
>
> --
> 2.6.2.307.g37023ba
>
>
> _______________________________________________
> Linux-nvme mailing list
> Linux-nvme at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-nvme
More information about the Linux-nvme
mailing list