[PATCH 1/3] accounting: task counters for disk/network

[PATCH 1/3] accounting: task counters for disk/network

[Gerlof Langeveld]

From: Gerlof Langeveld <gerlof@atcomputing.nl>

Proper performance analysis requires the availability of system level
and process level counters for CPU, memory, disk and network utilization.
The current kernel offers the system level counters, however process level
counters are only (sufficiently) available for CPU and memory utilization.

The kernel feature "task I/O accounting" currently maintains
per process counters for the number of bytes transferred to/from disk.
These counters are available via /proc/pid/io. It is still not possible
to find out which process issues the physical disk transfer. Besides,
not *all* disk transfers are accounted to processes (e.g. swap-transfers
by kswapd, journaling transfers).

This patch extends "task I/O accounting" by counting real *physical*
disk transfers per process and by counting IPv4/IPv6 socket transfers
per process.
The modified output generated for /proc/pid/io will be as follows:

  $ cat /proc/3179/io
  rchar: 49934
  wchar: 4
  syscr: 27
  syscw: 1
  read_bytes: 200704
  write_bytes: 4096
  cancelled_write_bytes: 0
  disk_read: 8                      <---- this line is added
  disk_read_sect: 392               <---- this line is added
  disk_write: 0                     <---- this line is added
  disk_write_sect: 0                <---- this line is added
  tcp_send: 0                       <---- this line is added
  tcp_send_bytes: 0                 <---- this line is added
  tcp_recv: 0                       <---- this line is added
  tcp_recv_bytes: 0                 <---- this line is added
  udp_send: 27                      <---- this line is added
  udp_send_bytes: 1296              <---- this line is added
  udp_recv: 27                      <---- this line is added
  udp_recv_bytes: 29484             <---- this line is added
  raw_send: 0                       <---- this line is added
  raw_recv: 0                       <---- this line is added

The performance monitor 'atop' uses a similar kernel patch for
several years already to be able to show these per process statistics.

Modified source files
  include/linux/task_io_accounting.h:   addition of new counters to the
                                        struct task_io_accounting

  fs/proc/base.c:                       generate output via /proc/pid/io

  block/ll_rw_blk.c:                    per process counting of physical
                                        disk access
 
  net/socket.c:                         per process counting of socket
                                        transfers

  kernel/acct.c:                        add number of disk reads/writes to
                                        standard accounting record

Since "task I/O accounting" is currently optional (CONFIG_TASK_IO_ACCOUNTING),
all modifications are ifdef'd with the same macro as well.
Patch applies to kernel version 2.6.24.4

Signed-off-by: Gerlof Langeveld <gerlof@atcomputing.nl>
---

diff -uprN -X linux-2.6.24.4-vanilla/Documentation/dontdiff linux-2.6.24.4-vanilla/block/ll_rw_blk.c linux-2.6.24.4-modified/block/ll_rw_blk.c
--- linux-2.6.24.4-vanilla/block/ll_rw_blk.c	2008-03-24 19:49:18.000000000 +0100
+++ linux-2.6.24.4-modified/block/ll_rw_blk.c	2008-03-25 13:52:14.000000000 +0100
@@ -2739,6 +2739,19 @@ static void drive_stat_acct(struct reque
 		disk_round_stats(rq->rq_disk);
 		rq->rq_disk->in_flight++;
 	}
+
+#ifdef CONFIG_TASK_IO_ACCOUNTING
+	switch (rw) {
+	case READ:
+		current->group_leader->ioac.dsk_rio += new_io;
+		current->group_leader->ioac.dsk_rsz += rq->nr_sectors;
+		break;
+	case WRITE:
+		current->group_leader->ioac.dsk_wio += new_io;
+		current->group_leader->ioac.dsk_wsz += rq->nr_sectors;
+		break;
+	}
+#endif
 }
 
 /*
diff -uprN -X linux-2.6.24.4-vanilla/Documentation/dontdiff linux-2.6.24.4-vanilla/fs/proc/base.c linux-2.6.24.4-modified/fs/proc/base.c
--- linux-2.6.24.4-vanilla/fs/proc/base.c	2008-03-24 19:49:18.000000000 +0100
+++ linux-2.6.24.4-modified/fs/proc/base.c	2008-03-25 13:52:14.000000000 +0100
@@ -2174,7 +2174,21 @@ static int proc_pid_io_accounting(struct
 #endif
 			"read_bytes: %llu\n"
 			"write_bytes: %llu\n"
-			"cancelled_write_bytes: %llu\n",
+			"cancelled_write_bytes: %llu\n"
+			"disk_read: %llu\n"
+			"disk_read_sect: %llu\n"
+			"disk_write: %llu\n"
+			"disk_write_sect: %llu\n"
+			"tcp_send: %llu\n"
+			"tcp_send_bytes: %llu\n"
+			"tcp_recv: %llu\n"
+			"tcp_recv_bytes: %llu\n"
+			"udp_send: %llu\n"
+			"udp_send_bytes: %llu\n"
+			"udp_recv: %llu\n"
+			"udp_recv_bytes: %llu\n"
+			"raw_send: %llu\n"
+			"raw_recv: %llu\n",
 #ifdef CONFIG_TASK_XACCT
 			(unsigned long long)task->rchar,
 			(unsigned long long)task->wchar,
@@ -2183,7 +2197,21 @@ static int proc_pid_io_accounting(struct
 #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)task->ioac.cancelled_write_bytes,
+			(unsigned long long)task->ioac.dsk_rio,
+			(unsigned long long)task->ioac.dsk_rsz,
+			(unsigned long long)task->ioac.dsk_wio,
+			(unsigned long long)task->ioac.dsk_wsz,
+			(unsigned long long)task->ioac.tcp_snd,
+			(unsigned long long)task->ioac.tcp_ssz,
+			(unsigned long long)task->ioac.tcp_rcv,
+			(unsigned long long)task->ioac.tcp_rsz,
+			(unsigned long long)task->ioac.udp_snd,
+			(unsigned long long)task->ioac.udp_ssz,
+			(unsigned long long)task->ioac.udp_rcv,
+			(unsigned long long)task->ioac.udp_rsz,
+			(unsigned long long)task->ioac.raw_snd,
+			(unsigned long long)task->ioac.raw_rcv);
 }
 #endif
 
diff -uprN -X linux-2.6.24.4-vanilla/Documentation/dontdiff linux-2.6.24.4-vanilla/include/linux/task_io_accounting.h linux-2.6.24.4-modified/include/linux/task_io_accounting.h
--- linux-2.6.24.4-vanilla/include/linux/task_io_accounting.h	2008-03-24 19:49:18.000000000 +0100
+++ linux-2.6.24.4-modified/include/linux/task_io_accounting.h	2008-03-25 13:52:14.000000000 +0100
@@ -30,6 +30,23 @@ struct task_io_accounting {
 	 * information loss in doing that.
 	 */
 	u64 cancelled_write_bytes;
+
+	/*
+	 * Number of physical reads and writes to disk by this task
+	 * and the accumulated size of these physical transfers.
+	 */
+	u64 dsk_rio, dsk_wio;
+	u64 dsk_rsz, dsk_wsz;
+
+	/*
+	 * Number of sends and receives issued for IPv4/IPv6 by
+	 * this task on TCP, UDP and raw sockets with their accumulated size.
+	 */
+	u64 tcp_snd, tcp_rcv;
+	u64 tcp_ssz, tcp_rsz;
+	u64 udp_snd, udp_rcv;
+	u64 udp_ssz, udp_rsz;
+	u64 raw_snd, raw_rcv;
 };
 #else
 struct task_io_accounting {
diff -uprN -X linux-2.6.24.4-vanilla/Documentation/dontdiff linux-2.6.24.4-vanilla/kernel/acct.c linux-2.6.24.4-modified/kernel/acct.c
--- linux-2.6.24.4-vanilla/kernel/acct.c	2008-03-24 19:49:18.000000000 +0100
+++ linux-2.6.24.4-modified/kernel/acct.c	2008-03-25 13:55:07.000000000 +0100
@@ -497,7 +497,11 @@ static void do_acct_process(struct file 
 	ac.ac_exitcode = pacct->ac_exitcode;
 	spin_unlock_irq(&current->sighand->siglock);
 	ac.ac_io = encode_comp_t(0 /* current->io_usage */);	/* %% */
+#ifdef CONFIG_TASK_IO_ACCOUNTING
+	ac.ac_rw = encode_comp_t(current->ioac.dsk_rio + current->ioac.dsk_wio);
+#else
 	ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
+#endif
 	ac.ac_swaps = encode_comp_t(0);
 
 	/*
diff -uprN -X linux-2.6.24.4-vanilla/Documentation/dontdiff linux-2.6.24.4-vanilla/net/socket.c linux-2.6.24.4-modified/net/socket.c
--- linux-2.6.24.4-vanilla/net/socket.c	2008-03-24 19:49:18.000000000 +0100
+++ linux-2.6.24.4-modified/net/socket.c	2008-03-25 13:52:14.000000000 +0100
@@ -551,10 +551,30 @@ static inline int __sock_sendmsg(struct 
 	si->size = size;
 
 	err = security_socket_sendmsg(sock, msg, size);
-	if (err)
-		return err;
+	if (!err)
+		err = sock->ops->sendmsg(iocb, sock, msg, size);
 
-	return sock->ops->sendmsg(iocb, sock, msg, size);
+#ifdef CONFIG_TASK_IO_ACCOUNTING
+	if (err >= 0 && sock->sk) {
+		switch (sock->sk->sk_family) {
+		case PF_INET:
+		case PF_INET6:
+			switch (sock->sk->sk_type) {
+			case SOCK_STREAM:
+				current->group_leader->ioac.tcp_snd++;
+				current->group_leader->ioac.tcp_ssz += size;
+				break;
+			case SOCK_DGRAM:
+				current->group_leader->ioac.udp_snd++;
+				current->group_leader->ioac.udp_ssz += size;
+				break;
+			case SOCK_RAW:
+				current->group_leader->ioac.raw_snd++;
+			}
+		}
+	}
+#endif
+       return err;
 }
 
 int sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
@@ -633,10 +653,31 @@ static inline int __sock_recvmsg(struct 
 	si->flags = flags;
 
 	err = security_socket_recvmsg(sock, msg, size, flags);
-	if (err)
-		return err;
+	if (!err)
+		err = sock->ops->recvmsg(iocb, sock, msg, size, flags);
 
-	return sock->ops->recvmsg(iocb, sock, msg, size, flags);
+#ifdef CONFIG_TASK_IO_ACCOUNTING
+	if (err >= 0 && sock->sk) {
+		switch (sock->sk->sk_family) {
+		case PF_INET:
+		case PF_INET6:
+			switch (sock->sk->sk_type) {
+			case SOCK_STREAM:
+				current->group_leader->ioac.tcp_rcv++;
+				current->group_leader->ioac.tcp_rsz += size;
+				break;
+			case SOCK_DGRAM:
+				current->group_leader->ioac.udp_rcv++;
+				current->group_leader->ioac.udp_rsz += size;
+				break;
+			case SOCK_RAW:
+				current->group_leader->ioac.raw_rcv++;
+				break;
+			}
+		}
+	}
+#endif
+	return err;
 }
 
 int sock_recvmsg(struct socket *sock, struct msghdr *msg,

Re: [PATCH 1/3] accounting: task counters for disk/network

[Andrew Morton]

On Wed, 2 Apr 2008 09:30:37 +0200
Gerlof Langeveld <gerlof@ATComputing.nl> wrote:

> 
> From: Gerlof Langeveld <gerlof@atcomputing.nl>

You sent three different patches, all with the same title.  Please don't do
that - choose unique, suitable and meaningful titles for each patch.

> Proper performance analysis requires the availability of system level
> and process level counters for CPU, memory, disk and network utilization.
> The current kernel offers the system level counters, however process level
> counters are only (sufficiently) available for CPU and memory utilization.
> 
> The kernel feature "task I/O accounting" currently maintains
> per process counters for the number of bytes transferred to/from disk.
> These counters are available via /proc/pid/io. It is still not possible
> to find out which process issues the physical disk transfer. Besides,
> not *all* disk transfers are accounted to processes (e.g. swap-transfers
> by kswapd, journaling transfers).
> 
> This patch extends "task I/O accounting" by counting real *physical*
> disk transfers per process and by counting IPv4/IPv6 socket transfers
> per process.
> The modified output generated for /proc/pid/io will be as follows:
> 
>   $ cat /proc/3179/io

/proc/pid/io is not the primary interface for this sort of accounting - it
was just tossed in there as an afterthought because it wasy easy.

This sort of accounting should be delivered across taskstats and
Documentation/accounting/getdelays.c should be suitably updated.

> --- linux-2.6.24.4-vanilla/block/ll_rw_blk.c	2008-03-24 19:49:18.000000000 +0100
> +++ linux-2.6.24.4-modified/block/ll_rw_blk.c	2008-03-25 13:52:14.000000000 +0100
> @@ -2739,6 +2739,19 @@ static void drive_stat_acct(struct reque
>  		disk_round_stats(rq->rq_disk);
>  		rq->rq_disk->in_flight++;
>  	}
> +
> +#ifdef CONFIG_TASK_IO_ACCOUNTING
> +	switch (rw) {
> +	case READ:
> +		current->group_leader->ioac.dsk_rio += new_io;
> +		current->group_leader->ioac.dsk_rsz += rq->nr_sectors;
> +		break;
> +	case WRITE:
> +		current->group_leader->ioac.dsk_wio += new_io;
> +		current->group_leader->ioac.dsk_wsz += rq->nr_sectors;
> +		break;
> +	}
> +#endif

For many workloads, this will cause almost all writeout to be accounted to
pdflush and perhaps kswapd.  This makes the per-task write accounting
largely unuseful.

Re: [PATCH 1/3] accounting: task counters for disk/network

[Gerlof Langeveld]

Op 03-04-2008, 12:54 Andrew Morton wrote:
> On Wed, 2 Apr 2008 09:30:37 +0200
> Gerlof Langeveld <gerlof@ATComputing.nl> wrote:
> 
> > 
> > From: Gerlof Langeveld <gerlof@atcomputing.nl>
> 
> You sent three different patches, all with the same title.  Please don't do
> that - choose unique, suitable and meaningful titles for each patch.

Sorry for that (I assumed the same title would correlate the three patches).

> > Proper performance analysis requires the availability of system level
> > and process level counters for CPU, memory, disk and network utilization.
> > The current kernel offers the system level counters, however process level
> > counters are only (sufficiently) available for CPU and memory utilization.
> > 
> > The kernel feature "task I/O accounting" currently maintains
> > per process counters for the number of bytes transferred to/from disk.
> > These counters are available via /proc/pid/io. It is still not possible
> > to find out which process issues the physical disk transfer. Besides,
> > not *all* disk transfers are accounted to processes (e.g. swap-transfers
> > by kswapd, journaling transfers).
> > 
> > This patch extends "task I/O accounting" by counting real *physical*
> > disk transfers per process and by counting IPv4/IPv6 socket transfers
> > per process.
> > The modified output generated for /proc/pid/io will be as follows:
> > 
> >   $ cat /proc/3179/io
> 
> /proc/pid/io is not the primary interface for this sort of accounting - it
> was just tossed in there as an afterthought because it wasy easy.
> 
> This sort of accounting should be delivered across taskstats and
> Documentation/accounting/getdelays.c should be suitably updated.

I must dive into the taskstats feature first, so I will deliver
a new patch later on.

> > --- linux-2.6.24.4-vanilla/block/ll_rw_blk.c	2008-03-24 19:49:18.000000000 +0100
> > +++ linux-2.6.24.4-modified/block/ll_rw_blk.c	2008-03-25 13:52:14.000000000 +0100
> > @@ -2739,6 +2739,19 @@ static void drive_stat_acct(struct reque
> >  		disk_round_stats(rq->rq_disk);
> >  		rq->rq_disk->in_flight++;
> >  	}
> > +
> > +#ifdef CONFIG_TASK_IO_ACCOUNTING
> > +	switch (rw) {
> > +	case READ:
> > +		current->group_leader->ioac.dsk_rio += new_io;
> > +		current->group_leader->ioac.dsk_rsz += rq->nr_sectors;
> > +		break;
> > +	case WRITE:
> > +		current->group_leader->ioac.dsk_wio += new_io;
> > +		current->group_leader->ioac.dsk_wsz += rq->nr_sectors;
> > +		break;
> > +	}
> > +#endif
> 
> For many workloads, this will cause almost all writeout to be accounted to
> pdflush and perhaps kswapd.  This makes the per-task write accounting
> largely unuseful.

There are several situations that writeouts are accounted to the user-process
itself, e.g. when issueing direct writes (open mode O_DIRECT) or synchronous
writes (open mode O_SYNC, syscall sync/fsync, synchronous file attribute,
synchronous mounted filesystem).

Apart from that, swapping out of process pages by kswapd is currently not
accounted at all as shown by the following snapshot of 'atop' on a heavily
swapping system:

ATOP - atdts              2008/04/07  19:01:24               10 seconds elapsed
......
MEM | tot    1.9G | free   14.1M | cache  11.0M | buff    0.6M | slab   22.4M |
SWP | tot    1.0G | free  513.6M |              | vmcom   2.3G | vmlim   2.0G |
PAG | scan   9865 | stall      0 |              | swin    4337 | swout   4718 |
DSK |         sda | busy    100% | read    1499 | write   1949 | avio    2 ms |

  PID  SYSCPU  USRCPU  VGROW  RGROW  RDDSK  WRDSK  ST EXC S  DSK CMD     1/1
13795   0.04s   0.01s     0K -3504K 12200K     0K  --   - D  71% memeater
27823   0.04s   0.00s     0K  -360K  5080K     0K  --   - D  29% appl
13791   0.00s   0.24s     0K     0K     0K     0K  --   - S   0% memeater
13793   0.00s   0.24s     0K     0K     0K     0K  --   - S   0% memeater
13792   0.00s   0.23s     0K    -4K     0K     0K  --   - S   0% memeater
13851   0.03s   0.00s     0K     0K     0K     0K  --   - S   0% atop
  236   0.03s   0.00s     0K     0K     0K     0K  --   - D   0% kswapd0

The process counters RDDSK and WRDSK are retrieved from the
standard /proc/pid/io.
There are no write-request accounted to any of the processes while 
1949 write requests have been issued on disk (line marked with DSK).
These writes should have been accounted to kswapd (writing to the swap
device).

With the additional counters maintained by this patch, every physical
I/O request is accounted to one of the processes which can be very useful
as an addition to the I/O accounting that is already implemented.
A snapshot of 'atop' on a swapping system that is patched:

ATOP - atdts              2008/04/07  19:01:17               10 seconds elapsed
......
MEM | tot    1.9G | free   13.8M | cache  11.0M | buff    0.6M | slab   22.4M |
SWP | tot    1.0G | free  513.4M |              | vmcom   2.3G | vmlim   2.0G |
PAG | scan   8021 | stall      0 |              | swin    3923 | swout   3367 |
DSK |         sda | busy    100% | read    1578 | write   1304 | avio    3 ms |

  PID  SYSCPU  USRCPU  VGROW  RGROW RDDSK WRDSK RNET SNET S  DSK CMD     1/1
27823   0.05s   0.00s     0K  1796K  1072    55    0    0 D  39% appl
  236   0.02s   0.00s     0K     0K     0   988    0    0 D  34% kswapd0
13795   0.04s   0.00s     0K -3824K   491   258    0    0 D  26% memeater
 2017   0.01s   0.00s     0K     0K     0    28    0    0 S   1% kjournald
 3218   0.00s   0.00s     0K     4K     6     0    0    0 S   0% sendmail

The process counters RDDSK and WRDSK now show the number of read and write
requests issued on disk for each process. The accumulated counters per process
correspond to the total number of requests measured on disk level (line marked
with DSK).

For read accounting it also useful to see the number of I/O requests issued
by a process (currently only the total number of Kbytes is accounted per
process). After all, 64 I/O requests of 4 Kbytes cause a heavier disk load
than 1 I/O request of 256 Kbytes.

So the extra counters can be considered as a useful addition to the I/O 
counters that are currently maintained.

Re: [PATCH 1/3] accounting: task counters for disk/network

[Andrew Morton]

On Tue, 8 Apr 2008 07:48:37 +0200 Gerlof Langeveld <gerlof@ATComputing.nl> wrote:

> > > --- linux-2.6.24.4-vanilla/block/ll_rw_blk.c	2008-03-24 19:49:18.000000000 +0100
> > > +++ linux-2.6.24.4-modified/block/ll_rw_blk.c	2008-03-25 13:52:14.000000000 +0100
> > > @@ -2739,6 +2739,19 @@ static void drive_stat_acct(struct reque
> > >  		disk_round_stats(rq->rq_disk);
> > >  		rq->rq_disk->in_flight++;
> > >  	}
> > > +
> > > +#ifdef CONFIG_TASK_IO_ACCOUNTING
> > > +	switch (rw) {
> > > +	case READ:
> > > +		current->group_leader->ioac.dsk_rio += new_io;
> > > +		current->group_leader->ioac.dsk_rsz += rq->nr_sectors;
> > > +		break;
> > > +	case WRITE:
> > > +		current->group_leader->ioac.dsk_wio += new_io;
> > > +		current->group_leader->ioac.dsk_wsz += rq->nr_sectors;
> > > +		break;
> > > +	}
> > > +#endif
> > 
> > For many workloads, this will cause almost all writeout to be accounted to
> > pdflush and perhaps kswapd.  This makes the per-task write accounting
> > largely unuseful.
> 
> There are several situations that writeouts are accounted to the user-process
> itself, e.g. when issueing direct writes (open mode O_DIRECT) or synchronous
> writes (open mode O_SYNC, syscall sync/fsync, synchronous file attribute,
> synchronous mounted filesystem).

yup.

> Apart from that, swapping out of process pages by kswapd is currently not
> accounted at all as shown by the following snapshot of 'atop' on a heavily
> swapping system:

Under heavy load, callers into alloc_pages() will themselves perform disk
writeout.  So under the proposed scheme, process A will be accounted for
writeout which was in fact caused by process B.

> So the extra counters can be considered as a useful addition to the I/O 
> counters that are currently maintained.

mmm, maybe.  But if we implement a partial solution like this we really
should have a plan to finish it off.

There have been numerous attempts at this, which tend to involve adding
backpointers to the pageframe structure and such.

This sort of accounting will presumably be needed by a disk bandwidth
cgroup controller.  Perhaps the containers/cgroup people have plans of code
already?

Re: [PATCH 1/3] accounting: task counters for disk/network

[Paul Menage]

On Mon, Apr 7, 2008 at 11:10 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>
>  This sort of accounting will presumably be needed by a disk bandwidth
>  cgroup controller.  Perhaps the containers/cgroup people have plans of code
>  already?
>

Yes, there have been various cgroup block-I/O subsystems proposed. I
know that at least the one posted by Hirokazu Takahashi
<taka@valinux.co.jp> uses the same per-page cgroup pointer as the
memory controller.

Paul

Re: [PATCH 1/3] accounting: task counters for disk/network

[Hirokazu Takahashi]

Hi Gerlof,

> >  This sort of accounting will presumably be needed by a disk bandwidth
> >  cgroup controller.  Perhaps the containers/cgroup people have plans of code
> >  already?
> >
> 
> Yes, there have been various cgroup block-I/O subsystems proposed. I
> know that at least the one posted by Hirokazu Takahashi
> <taka@valinux.co.jp> uses the same per-page cgroup pointer as the
> memory controller.

Yes, I'm working on this.

linux-2.6.25-rc series now have the memory controller in them, which
supports to get the cgroup from any pageframe. I made a block-I/O
controller on it experimentally.

If you use this controller with dm-ioband, which is an engine implemented
as a device mapper module to control the bandwidth of block I/Os,
you can also get "cgroup block I/O accounting" from it.

I guess you can enhance this controller to track the I/Os per process
if you really want to. But it will cause extra overhead which I think
you may not ignore.

Thanks,
Hirokazu Takahashi.