[PATCH] distinct tgid/tid I/O statistics (was: taskstats and /proc/.../ioasymmetry?)
From: Andrea Righi
Date: Fri May 16 2008 - 16:38:46 EST
Balbir Singh wrote:
Mark Seger wrote:
If you look at /proc/pid/stat, you can get the total CPU consumed by a
process. If you look at /proc/pid/task/tid/stat you can get the cpu
consumed by a thread and if the tid is that of the parent you only gets
its consumption as opposed to all its children.
I was surprised to see that the way process I/O is reported doesn't
follow this model. There are no /prod/pid/task/tid/io entries but
rather you need to look in /proc/tid/io. While I view this as a minor
inconvenience, I can certainly live with it. However, /proc/pid/io does
not show the aggregate I/O numbers for the whole process and that both
surprises and disappoints. This means if I have a process that starts a
bunch of worker threads that do the real work and I want to find the top
I/O consumers I can't simply walk the /proc/pid tree but rather have to
look at all the threads of each process and add them up.
Or am I missing something?
I looked through the code and your argument seems to be correct. The behaviour
is inconsistent w.r.t. other statistics like utime and stime. We currently
accumulate tgid information in signal_struct, we need to do something similar
for io as well. If nobody gets to it by the time I finish my backlog, I'll try
and get to it.
Balbir, Mark,
what do you think about the following approach?
Patch against 2.6.25.4, tested in KVM.
-Andrea
--
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.
Bug reported by Mark Seger <Mark.Seger@xxxxxx>.
Signed-off-by: Andrea Righi <righiandr@xxxxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 83 +++++++++++++++++++++++++++++++++++++++++++------
include/linux/sched.h | 4 ++
kernel/exit.c | 27 ++++++++++++++++
kernel/fork.c | 6 +++
4 files changed, 110 insertions(+), 10 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 81d7d14..23763c5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2255,8 +2255,58 @@ 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)
{
+ unsigned long flags;
+ u64 rchar, wchar, syscr, syscw;
+ struct task_io_accounting ioac;
+
+ if (!whole) {
+#ifdef CONFIG_TASK_XACCT
+ rchar = task->rchar;
+ wchar = task->wchar;
+ syscr = task->syscr;
+ syscw = task->syscw;
+#endif
+ memcpy(&ioac, &task->ioac, sizeof(ioac));
+ } else {
+ rchar = wchar = syscr = syscw = 0;
+ memset(&ioac, 0, sizeof(ioac));
+ rcu_read_lock();
+ if (lock_task_sighand(task, &flags)) {
+ struct signal_struct *sig = task->signal;
+ struct task_struct *t = task;
+
+ do {
+#ifdef CONFIG_TASK_XACCT
+ rchar += t->rchar;
+ wchar += t->wchar;
+ syscr += t->syscr;
+ syscw += t->syscw;
+#endif
+ 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);
+
+#ifdef CONFIG_TASK_XACCT
+ rchar += sig->rchar;
+ wchar += sig->wchar;
+ syscr += sig->syscr;
+ syscw += sig->syscw;
+#endif
+ 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);
+ }
+ rcu_read_unlock();
+ }
+
return sprintf(buffer,
#ifdef CONFIG_TASK_XACCT
"rchar: %llu\n"
@@ -2268,16 +2318,26 @@ static int proc_pid_io_accounting(struct task_struct *task, char *buffer)
"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,
+ (unsigned long long)rchar,
+ (unsigned long long)wchar,
+ (unsigned long long)syscr,
+ (unsigned long long)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)ioac.read_bytes,
+ (unsigned long long)ioac.write_bytes,
+ (unsigned long long)ioac.cancelled_write_bytes);
+}
+
+static int proc_tid_io_accounting(struct task_struct *task, char *buffer)
+{
+ return do_io_accounting(task, buffer, 0);
}
-#endif
+
+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
@@ -2348,7 +2408,7 @@ 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
};
@@ -2675,6 +2735,9 @@ 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,
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6a1e7af..ebf8b45 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -504,6 +504,10 @@ 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
diff --git a/kernel/exit.c b/kernel/exit.c
index 073005b..1a35583 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -114,6 +114,18 @@ 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. */
}
@@ -1250,6 +1262,21 @@ static int wait_task_zombie(struct task_struct *p, int noreap,
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);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 9c042f9..b8f408e 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -924,6 +924,12 @@ 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]);
--
1.5.4.3
--
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