Commit 297c5d92 authored by Andrea Righi's avatar Andrea Righi Committed by Linus Torvalds
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task IO accounting: provide distinct tgid/tid I/O statistics 



Report per-thread I/O statistics in /proc/pid/task/tid/io and aggregate
parent I/O statistics in /proc/pid/io.  This approach follows the same
model used to account per-process and per-thread CPU times.

As a practial application, this allows for example to quickly find the top
I/O consumer when a process spawns many child threads that perform the
actual I/O work, because the aggregated I/O statistics can always be found
in /proc/pid/io.

[ Oleg Nesterov points out that we should check that the task is still
  alive before we iterate over the threads, but also says that we can do
  that fixup on top of this later.  - Linus ]

Acked-by: default avatarBalbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrea Righi <righi.andrea@gmail.com>
Cc: Matt Heaton <matt@hostmonster.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Acked-by-with-comments: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0c18d7a5

fs/proc/base.c

+71 −15
Original line number Diff line number Diff line
@@ -2376,29 +2376,82 @@ static int proc_base_fill_cache(struct file *filp, void *dirent, 
}



#ifdef CONFIG_TASK_IO_ACCOUNTING

static int proc_pid_io_accounting(struct task_struct *task, char *buffer)

static int do_io_accounting(struct task_struct *task, char *buffer, int whole)

{

	u64 rchar, wchar, syscr, syscw;

	struct task_io_accounting ioac;



	if (!whole) {

		rchar = task->rchar;

		wchar = task->wchar;

		syscr = task->syscr;

		syscw = task->syscw;

		memcpy(&ioac, &task->ioac, sizeof(ioac));

	} else {

		unsigned long flags;

		struct task_struct *t = task;

		rchar = wchar = syscr = syscw = 0;

		memset(&ioac, 0, sizeof(ioac));



		rcu_read_lock();

		do {

			rchar += t->rchar;

			wchar += t->wchar;

			syscr += t->syscr;

			syscw += t->syscw;



			ioac.read_bytes += t->ioac.read_bytes;

			ioac.write_bytes += t->ioac.write_bytes;

			ioac.cancelled_write_bytes +=

					t->ioac.cancelled_write_bytes;

			t = next_thread(t);

		} while (t != task);

		rcu_read_unlock();



		if (lock_task_sighand(task, &flags)) {

			struct signal_struct *sig = task->signal;



			rchar += sig->rchar;

			wchar += sig->wchar;

			syscr += sig->syscr;

			syscw += sig->syscw;



			ioac.read_bytes += sig->ioac.read_bytes;

			ioac.write_bytes += sig->ioac.write_bytes;

			ioac.cancelled_write_bytes +=

					sig->ioac.cancelled_write_bytes;



			unlock_task_sighand(task, &flags);

		}

	}



	return sprintf(buffer,

#ifdef CONFIG_TASK_XACCT

			"rchar: %llu\n"

			"wchar: %llu\n"

			"syscr: %llu\n"

			"syscw: %llu\n"

#endif

			"read_bytes: %llu\n"

			"write_bytes: %llu\n"

			"cancelled_write_bytes: %llu\n",

#ifdef CONFIG_TASK_XACCT

			(unsigned long long)task->rchar,

			(unsigned long long)task->wchar,

			(unsigned long long)task->syscr,

			(unsigned long long)task->syscw,

#endif

			(unsigned long long)task->ioac.read_bytes,

			(unsigned long long)task->ioac.write_bytes,

			(unsigned long long)task->ioac.cancelled_write_bytes);

			(unsigned long long)rchar,

			(unsigned long long)wchar,

			(unsigned long long)syscr,

			(unsigned long long)syscw,

			(unsigned long long)ioac.read_bytes,

			(unsigned long long)ioac.write_bytes,

			(unsigned long long)ioac.cancelled_write_bytes);

}

#endif



static int proc_tid_io_accounting(struct task_struct *task, char *buffer)

{

	return do_io_accounting(task, buffer, 0);

}



static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)

{

	return do_io_accounting(task, buffer, 1);

}

#endif /* CONFIG_TASK_IO_ACCOUNTING */



/*

 * Thread groups
@@ -2470,7 +2523,7 @@ static const struct pid_entry tgid_base_stuff[] = { 
	REG("coredump_filter", S_IRUGO|S_IWUSR, coredump_filter),

#endif

#ifdef CONFIG_TASK_IO_ACCOUNTING

	INF("io",	S_IRUGO, pid_io_accounting),

	INF("io",	S_IRUGO, tgid_io_accounting),

#endif

};
@@ -2797,6 +2850,9 @@ static const struct pid_entry tid_base_stuff[] = { 
#ifdef CONFIG_FAULT_INJECTION

	REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),

#endif

#ifdef CONFIG_TASK_IO_ACCOUNTING

	INF("io",	S_IRUGO, tid_io_accounting),

#endif

};



static int proc_tid_base_readdir(struct file * filp,

include/linux/sched.h

+4 −0
Original line number Diff line number Diff line
@@ -506,6 +506,10 @@ struct signal_struct { 
	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;

	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;

	unsigned long inblock, oublock, cinblock, coublock;

#ifdef CONFIG_TASK_XACCT

	u64 rchar, wchar, syscr, syscw;

#endif

	struct task_io_accounting ioac;



	/*

	 * Cumulative ns of scheduled CPU time for dead threads in the

kernel/exit.c

+27 −0
Original line number Diff line number Diff line
@@ -120,6 +120,18 @@ static void __exit_signal(struct task_struct *tsk) 
		sig->nivcsw += tsk->nivcsw;

		sig->inblock += task_io_get_inblock(tsk);

		sig->oublock += task_io_get_oublock(tsk);

#ifdef CONFIG_TASK_XACCT

		sig->rchar += tsk->rchar;

		sig->wchar += tsk->wchar;

		sig->syscr += tsk->syscr;

		sig->syscw += tsk->syscw;

#endif /* CONFIG_TASK_XACCT */

#ifdef CONFIG_TASK_IO_ACCOUNTING

		sig->ioac.read_bytes += tsk->ioac.read_bytes;

		sig->ioac.write_bytes += tsk->ioac.write_bytes;

		sig->ioac.cancelled_write_bytes +=

					tsk->ioac.cancelled_write_bytes;

#endif /* CONFIG_TASK_IO_ACCOUNTING */

		sig->sum_sched_runtime += tsk->se.sum_exec_runtime;

		sig = NULL; /* Marker for below. */

	}
@@ -1366,6 +1378,21 @@ static int wait_task_zombie(struct task_struct *p, int options, 
		psig->coublock +=

			task_io_get_oublock(p) +

			sig->oublock + sig->coublock;

#ifdef CONFIG_TASK_XACCT

		psig->rchar += p->rchar + sig->rchar;

		psig->wchar += p->wchar + sig->wchar;

		psig->syscr += p->syscr + sig->syscr;

		psig->syscw += p->syscw + sig->syscw;

#endif /* CONFIG_TASK_XACCT */

#ifdef CONFIG_TASK_IO_ACCOUNTING

		psig->ioac.read_bytes +=

			p->ioac.read_bytes + sig->ioac.read_bytes;

		psig->ioac.write_bytes +=

			p->ioac.write_bytes + sig->ioac.write_bytes;

		psig->ioac.cancelled_write_bytes +=

				p->ioac.cancelled_write_bytes +

				sig->ioac.cancelled_write_bytes;

#endif /* CONFIG_TASK_IO_ACCOUNTING */

		spin_unlock_irq(&p->parent->sighand->siglock);

	}

kernel/fork.c

+6 −0
Original line number Diff line number Diff line
@@ -812,6 +812,12 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 
	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;

	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;

	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;

#ifdef CONFIG_TASK_XACCT

	sig->rchar = sig->wchar = sig->syscr = sig->syscw = 0;

#endif

#ifdef CONFIG_TASK_IO_ACCOUNTING

	memset(&sig->ioac, 0, sizeof(sig->ioac));

#endif

	sig->sum_sched_runtime = 0;

	INIT_LIST_HEAD(&sig->cpu_timers[0]);

	INIT_LIST_HEAD(&sig->cpu_timers[1]);

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