hi all
The last month or so, I've been trying to make a particular configuration work
with Linux-2.4.17 and other 2.4.x kernels. Two major bugs have been blocking
my way into the light. Below follows a detailed description on both bugs. One
of them seems to be solved in the latests -rmap patches. The other is still
unsolved.
CONFIGURATION INTRO
The test has been performed on two equally configured computers, giving the
same results, telling the chance of hardware failure is rather small.
Config:
1xAthlon 1133
2x512MB (1GB) SRAM
Asus A7S-VM motherboard with
Realtek 10/100Mbps card
ATA100
Sound+VGA+USB+other crap
1xPromise ATA133 controller
2xWDC 120GB drives (with ATA100 cabeling connected to Promise controller)
1xWDC 20GB drive (connected to motherboard - configured as the boot device)
1xIntel desktop gigE card (e1000 driver - modular)
Server is configured with console on serial port
Highmem is disabled
The two 120GB drives is configured in RAID-0 with chunk size [256|512|1024]
I have tried several different file systems - same error
Versions tested:
Linux-2.4.1([3-7]|8-pre.) tested. All buggy. Bug #1 was fixed in -rmap11c
TEST SETUP
Reading 100 500MB files with dd, tux, apache, cat, something, and redirecting
the output to /dev/null. With tux/apache, I used another computer using wget
to retrieve the same amount of data.
The test scripts look something like this
#!/bin/bash
dd if=file0000 of=/dev/null &
dd if=file0001 of=/dev/null &
dd if=file0002 of=/dev/null &
dd if=file0003 of=/dev/null &
...
dd if=file0099 of=/dev/null &
or similar - just with wget -O /dev/null ... &
BUGS
Bug #1:
When (RAMx2) bytes has been read from disk, I/O as reported from vmstat drops
to a mere 1MB/s
When reading starts, the speed is initially high. Then, slowly, the speed
decreases until it goes to something close to a complete halt (see output from
vmstat below).
# vmstat 2
r b w swpd free buff cache si so bi bo in cs us sy id
0 200 1 1676 3200 3012 786004 0 292 42034 298 791 745 4 29 67
0 200 1 1676 3308 3136 785760 0 0 44304 0 748 758 3 15 82
0 200 1 1676 3296 3232 785676 0 0 44236 0 756 710 2 23 75
0 200 1 1676 3304 3356 785548 0 0 38662 70 778 791 3 19 78
0 200 1 1676 3200 3456 785552 0 0 33536 0 693 594 3 13 84
1 200 0 1676 3224 3528 785192 0 0 35330 24 794 712 3 16 81
0 200 0 1676 3304 3736 784324 0 0 30524 74 725 793 12 14 74
0 200 0 1676 3256 3796 783664 0 0 29984 0 718 826 4 10 86
0 200 0 1676 3288 3868 783592 0 0 25540 152 763 812 3 17 80
0 200 0 1676 3276 3908 783472 0 0 22820 0 693 731 0 7 92
0 200 0 1676 3200 3964 783540 0 0 23312 6 759 827 4 11 85
0 200 0 1676 3308 3984 783452 0 0 17506 0 687 697 0 11 89
0 200 0 1676 3388 4012 783888 0 0 14512 0 671 638 1 5 93
0 200 0 2188 3208 4048 784156 0 512 16104 548 707 833 2 10 88
0 200 0 3468 3204 4048 784788 0 66 8220 66 628 662 0 3 96
0 200 0 3468 3296 4060 784680 0 0 1036 6 687 714 1 6 93
0 200 0 3468 3316 4060 784668 0 0 1018 0 613 631 1 2 97
0 200 0 3468 3292 4060 784688 0 0 1034 0 617 638 0 3 97
0 200 0 3468 3200 4068 784772 0 0 1066 6 694 727 2 4 94
Bug #2:
Doing the same test on Rik's -rmap(.*) somehow fixes Bug #1, and makes room
for another bug to come out.
Doing the same test, I can, with -rmap, get some 33-35MB/s sustained from
/dev/md0 to memory. This is all good, but when doing this test, only 40 of the
original processes ever finish. The same error occurs both locally (dd) and
remotely (tux). If new i/o requests is issued to the same device, they don't
hang. If tux is restarted, it works fine afterwards.
Please - anyone - help me with this. I've been trying to setup this system for
almost two months now, fighting various bugs.
Best regards
roy
-- Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCAComputers are like air conditioners. They stop working when you open Windows.
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This archive was generated by hypermail 2b29 : Thu Jan 31 2002 - 21:01:35 EST