Hi, Tsuruta.

> In addition, I got the following message during test #2. Program
> "ioload", our benchmark program, was blocked more than 120 seconds.
> Do you see any problems?

No.
I tried to test in  environment which runs from 1 to 200 processes
per group.
However, such message was not output.

> The result of test #1 is close to your estimation, but the result
> of test #2 is not, the gap between the estimation and the result
> increased.

In the above my test, the gap between the estimation and the result
is increasing as a process increases.

And, in native CFQ with ionice command, this situation is a similar.
These circumstances are shown in the case of more than processes of total 200.

I'll investigate this problem continuously.


Thanks,
  Satoshi Uchida.

> -----Original Message-----
> From: Ryo Tsuruta [mailto:ryov@valinux.co.jp]
> Sent: Tuesday, June 03, 2008 5:16 PM
> To: s-uchida@ap.jp.nec.com
> Cc: axboe@kernel.dk; vtaras@openvz.org;
> containers@lists.linux-foundation.org; tom-sugawara@ap.jp.nec.com;
> linux-kernel@vger.kernel.org
> Subject: Re: [RFC][v2][patch 0/12][CFQ-cgroup]Yet another I/O bandwidth
> controlling subsystem for CGroups based on CFQ
> 
> Hi Uchida-san,
> 
> > I report my tests.
> 
> I did a similar test to yours. I increased the number of I/Os
> which are issued simultaneously up to 100 per cgroup.
> 
>   Procedures:
>     o Prepare 300 files which size is 250MB on 1 partition sdb3
>     o Create three groups with priority 0, 4 and 7.
>     o Run many processes issuing random direct I/O with 4KB data on each
>       files in three groups.
>           #1 Run  25 processes issuing read I/O only per group.
>           #2 Run 100 processes issuing read I/O only per group.
>     o Count up the number of I/Os which have done in 10 minutes.
> 
>                The number of I/Os (percentage to total I/O)
>      --------------------------------------------------------------
>     | group       |  group 1   |  group 2   |  group 3   |  total  |
>     | priority    | 0(highest) |     4      |  7(lowest) |  I/Os   |
>     |-------------+------------+------------+------------+---------|
>     | Estimate    |            |            |            |         |
>     | Performance |    61.5%   |    30.8%   |    7.7%    |         |
>     |-------------+------------+------------+------------|---------|
>     | #1  25procs | 52763(57%) | 30811(33%) |  9575(10%) |  93149  |
>     | #2 100procs | 24949(40%) | 21325(34%) | 16508(26%) |  62782  |
>      --------------------------------------------------------------
> 
> The result of test #1 is close to your estimation, but the result
> of test #2 is not, the gap between the estimation and the result
> increased.
> 
> In addition, I got the following message during test #2. Program
> "ioload", our benchmark program, was blocked more than 120 seconds.
> Do you see any problems?
> 
> INFO: task ioload:8456 blocked for more than 120 seconds.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> ioload        D 00000008  2772  8456   8419
>        f72eb740 00200082 c34862c0 00000008 c3565170 c35653c0 c2009d80
>        00000001
>        c1d1bea0 00200046 ffffffff f6ee039c 00000000 00000000 00000000
>        c2009d80
>        018db000 00000000 f71a6a00 c0604fb6 00000000 f71a6bc8 c04876a4
>        00000000
> Call Trace:
>  [<c0604fb6>] io_schedule+0x4a/0x81
>  [<c04876a4>] __blockdev_direct_IO+0xa04/0xb54
>  [<c04a3aa2>] ext2_direct_IO+0x35/0x3a
>  [<c04a4757>] ext2_get_block+0x0/0x603
>  [<c044ab81>] generic_file_direct_IO+0x103/0x118
>  [<c044abe6>] generic_file_direct_write+0x50/0x13d
>  [<c044b59e>] __generic_file_aio_write_nolock+0x375/0x4c3
>  [<c046e571>] link_path_walk+0x86/0x8f
>  [<c044a1e8>] find_lock_page+0x19/0x6d
>  [<c044b73e>] generic_file_aio_write+0x52/0xa9
>  [<c0466256>] do_sync_write+0xbf/0x100
>  [<c042ca44>] autoremove_wake_function+0x0/0x2d
>  [<c0413366>] update_curr+0x83/0x116
>  [<c0605280>] mutex_lock+0xb/0x1a
>  [<c04b653b>] security_file_permission+0xc/0xd
>  [<c0466197>] do_sync_write+0x0/0x100
>  [<c046695d>] vfs_write+0x83/0xf6
>  [<c0466ea9>] sys_write+0x3c/0x63
>  [<c04038de>] syscall_call+0x7/0xb
>  [<c0600000>] print_cpu_info+0x27/0x92
>  =======================
> 
> Thanks,
> Ryo Tsuruta

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