dm-band: The I/O bandwidth controller: Performance Report

[Ryo Tsuruta]

Hi,

Now I report the result of dm-band bandwidth control test I did yesterday.
I've got really good results that dm-band works as I expected. I made
several band-groups on several disk partitions and gave them heavy I/O loads.

Hardware Spec.
==============
  DELL Dimention E521:

  Linux kappa.local.valinux.co.jp 2.6.23.14 #1 SMP
    Thu Jan 24 17:24:59 JST 2008 i686 athlon i386 GNU/Linux
  Detected 2004.217 MHz processor.
  CPU0: AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ stepping 02
  Memory: 966240k/981888k available (2102k kernel code, 14932k reserved,
    890k data, 216k init, 64384k highmem)
  scsi 2:0:0:0: Direct-Access     ATA      ST3250620AS     3.AA PQ: 0 ANSI: 5
  sd 2:0:0:0: [sdb] 488397168 512-byte hardware sectors (250059 MB)
  sd 2:0:0:0: [sdb] Write Protect is off
  sd 2:0:0:0: [sdb] Mode Sense: 00 3a 00 00
  sd 2:0:0:0: [sdb] Write cache: enabled, read cache: enabled,
    doesn't support DPO or FUA
  sdb: sdb1 sdb2 < sdb5 sdb6 sdb7 sdb8 sdb9 sdb10 sdb11 sdb12 sdb13 sdb14
    sdb15 >

The results of bandwidth control test on partitions
===================================================

The configurations of the test #1:
   o Prepare three partitions sdb5, sdb6 and sdb7.
   o Give weights of 40, 20 and 10 to sdb5, sdb6 and sdb7 respectively.
   o Run 128 processes issuing random read/write direct I/O with 4KB data
     on each device at the same time.
   o Count up the number of I/Os and sectors which have done in 60 seconds.

                The result of the test #1
 ---------------------------------------------------------------------------
|     device      |       sdb5        |       sdb6        |      sdb7       |
|     weight      |    40 (57.0%)     |     20 (29.0%)    |    10 (14.0%)   |
|-----------------+-------------------+-------------------+-----------------|
|   I/Os (r/w)    |  6640( 3272/ 3368)|  3434( 1719/ 1715)|  1689( 857/ 832)|
|  sectors (r/w)  | 53120(26176/26944)| 27472(13752/13720)| 13512(6856/6656)|
|  ratio to total |       56.4%       |       29.2%       |      14.4%      |
 ---------------------------------------------------------------------------


The configurations of the test #2:
   o The configurations are the same as the test #1 except this test doesn't
     run any processes issuing I/Os on sdb6.

                The result of the test #2
 ---------------------------------------------------------------------------
|     device      |       sdb5        |       sdb6        |      sdb7       |
|     weight      |    40 (57.0%)     |     20 (29.0%)    |    10 (14.0%)   |
|-----------------+-------------------+-------------------+-----------------|
|   I/Os (r/w)    |  9566(4815/  4751)|     0(    0/    0)|  2370(1198/1172)|
|  sectors (r/w)  | 76528(38520/38008)|     0(    0/    0)| 18960(9584/9376)|
|  ratio to total |       76.8%       |        0.0%       |     23.2%       |
 ---------------------------------------------------------------------------

The results of bandwidth control test on band-groups.
=====================================================
The configurations of the test #3:
   o Prepare three partitions sdb5 and sdb6.
   o Create two extra band-groups on sdb5, the first is of user1 and the
     second is of user2.
   o Give weights of 40, 20, 10 and 10 to the user1 band-group, the user2
     band-group, the default group of sdb5 and sdb6 respectively.
   o Run 128 processes issuing random read/write direct I/O with 4KB data
     on each device at the same time.
   o Count up the number of I/Os and sectors which have done in 60 seconds.

                The result of the test #3
 ---------------------------------------------------------------------------
|dev|                          sdb5                        |      sdb6      |
|---+------------------------------------------------------+----------------|
|usr|     user1        |      user2       |  other users   |   all users    |
|wgt|   40 (50.0%)     |    20 (25.0%)    |   10 (12.5%)   |   10 (12.5%)   |
|---+------------------+------------------+----------------+----------------|
|I/O| 5951( 2940/ 3011)| 3068( 1574/ 1494)| 1663( 828/ 835)| 1663( 810/ 853)|
|sec|47608(23520/24088)|24544(12592/11952)|13304(6624/6680)|13304(6480/6824)|
| % |     48.2%        |       24.9%      |      13.5%     |      13.5%     |
 ---------------------------------------------------------------------------

The configurations of the test #4:
   o The configurations are the same as the test #3 except this test doesn't
     run any processes issuing I/Os on the user2 band-group.

                The result of the test #4
 ---------------------------------------------------------------------------
|dev|                          sdb5                        |     sdb6       |
|---+------------------------------------------------------+----------------|
|usr|     user1        |      user2       |  other users   |   all users    |
|wgt|   40 (50.0%)     |    20 (25.0%)    |   10 (12.5%)   |   10 (12.5%)   |
|---+------------------+------------------+----------------+----------------|
|I/O| 8002( 3963/ 4039)|    0(    0/    0)| 2056(1021/1035)| 2008( 998/1010)|
|sec|64016(31704/32312)|    0(    0/    0)|16448(8168/8280)|16064(7984/8080)|
| % |     66.3%        |        0.0%      |      17.0%     |      16.6%     |
 ---------------------------------------------------------------------------

Conclusions and future works
============================
Dm-band works well with random I/Os. I have a plan on running some tests
using various real applications such as databases or file servers.
If you have any other good idea to test dm-band, please let me know.

Thank you,
Ryo Tsuruta.
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