[Bug 221437] Re: very bad I/O performance with linux kernel in Hardy

[Ritesh Raj Sarraf]

Attached is the output of iostat when the copy was taking place.
Interesting thing to notice is that the I/O starts up at a good speed, copies at good speed and then eventually the performance starts degrading.

I'm also adding the output of top which is pretty interesting....
rrs at learner:~$ top
top - 02:17:22 up  4:11,  1 user,  load average: 8.93, 8.99, 5.34
Tasks: 152 total,   4 running, 148 sleeping,   0 stopped,   0 zombie
Cpu(s): 61.3%us, 28.9%sy,  1.2%ni,  0.0%id,  0.0%wa,  0.5%hi,  8.1%si,  0.0%st
Mem:   2074320k total,  2018768k used,    55552k free,     3588k buffers
Swap:  2621432k total,    38436k used,  2582996k free,  1088672k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 6460 rrs       20   0 38224  19m  15m R   57  1.0  11:29.92 kded
 7419 rrs       20   0  785m 545m  35m R   49 26.9   7:01.30 kontact
13698 rrs       20   0  181m  67m  26m S   38  3.3   0:46.24 firefox
 6613 rrs       20   0 95940  47m  25m S   20  2.4   2:50.79 kopete
 5585 root      20   0 79964  51m 5468 R   16  2.6   5:09.88 Xorg
25743 rrs       20   0  2308 1144  856 R   15  0.1   0:04.24 top
 6824 rrs       20   0 34048  16m  11m S    7  0.8   0:38.62 konsole
 2663 root      15  -5     0    0    0 S    5  0.0   8:57.19 kcryptd
18011 rrs       39  19 93568  30m  10m S    3  1.5   3:50.96 beagled-helper
   48 root      15  -5     0    0    0 S    1  0.0   0:09.40 kblockd/1
 6455 rrs       20   0 25912 3260 1688 S    1  0.2   0:18.60 dcopserver
 6637 rrs       20   0 35012 3724 2920 S    1  0.2   0:03.50 pulseaudio
 6642 rrs       20   0 31892  11m 9148 S    1  0.6   0:03.48 klipper
 6522 rrs       20   0 31624 8160 5812 S    1  0.4   0:13.23 artsd
    1 root      20   0  2844 1692  544 S    0  0.1   0:01.42 init
    2 root      15  -5     0    0    0 S    0  0.0   0:00.00 kthreadd


This was captured after around 20 seconds when I interrupted the copy (Sorry, no early could I do it. The machine was not that responsive at that stage). Interesting thing to note is that why are the KDE applications eating up so much of CPU cycles. I'm doing the copy from the KDE filemanager, Dolphin.

Also to point is that when I/O is run, kcryptd takes up a good amount of
CPU cycles (around 20-25%), but I think that should be correct because
encryption/decryption itself is expensive. What is most bothering is the
degradation of the entire OS during such I/O.

** Attachment added: "log"
   http://launchpadlibrarian.net/13864209/log

-- 
very bad I/O performance with linux kernel in Hardy
https://bugs.launchpad.net/bugs/221437
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