blk-13B

From: Giuliano Pochini (pochini@denise.shiny.it)
Date: Sat Jan 13 2001 - 11:41:28 EST


Hi!

I found the time to make some tests with 2.4 and the blk-13B patch.
It performs very well, no process starvation, no missed merges,
etc., but sometimes it happens dbflush and kswapd start eating
100% CPU for about 20-30 secs.:

 11:02am up 18 min, 5 users, load average: 2.74, 1.97, 1.15
66 processes: 60 sleeping, 6 running, 0 zombie, 0 stopped
CPU states: 2.7% user, 97.2% system, 0.0% nice, 0.0% idle
Mem: 189568K av, 188520K used, 1048K free, 209144K shrd, 1168K buff
Swap: 262136K av, 0K used, 262136K free 122764K cached

 PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND
   3 root 20 0 0 0 0 SW 0 45.1 0.0 0:21 kswapd
   5 root 14 0 0 0 0 RW 0 44.5 0.0 0:29 bdflush
 606 Giu 9 0 464 464 352 R 0 3.6 0.2 0:02 cp
 543 Giu 9 0 604 604 472 S 0 1.9 0.3 0:14 vmstat

vmstat doesn't show anything strange at the same time:

   procs memory swap io system cpu
 r b w swpd free buff cache si so bi bo in cs us sy id
 2 0 0 0 1048 1304 122564 0 0 8960 4486 156 771 11 25 64
 3 0 0 0 1048 1304 122564 0 0 9856 4996 123 622 3 30 67
 1 0 1 0 1048 1304 122564 0 0 4096 1867 62 431 1 76 23
 2 0 1 0 1048 1304 122560 0 0 1920 963 26 130 1 99 0
 4 1 2 0 1048 1304 122564 0 0 1536 647 164 271 3 97 0
 2 0 2 0 1048 1304 122564 0 0 760 516 139 482 6 94 0
 1 1 2 0 1048 1304 122560 0 0 896 461 275 932 10 90 0
 1 0 2 0 1048 1304 122552 0 0 672 452 130 988 7 93 0
 1 0 2 0 1048 1304 122552 0 0 896 520 180 1905 11 89 0
 2 0 2 0 1052 1304 122552 0 0 512 515 26 462 4 96 0
 1 1 2 0 1048 1304 122556 0 0 740 519 109 428 1 99 0
 3 0 1 0 1048 1228 122624 0 0 1052 516 23 175 4 96 0

The scsi driver reported it was writing large contiguous blocks and, 30secs
later, a few 10s of smaller non mergeable block. It's ok IMO.
ps doesn't show anything useful:

[Giu@Jay Giu]$ ps -xao cmd,wchan
CMD WCHAN
init do_select
[keventd] context_thread
[kswapd] -
[kreclaimd] kreclaimd
[bdflush] -
[kupdate] kupdate
[khubd] usb_hub_thread

The test is a large file copy from the HD to my MO. During the cp and
now there's nothing on the swap.
My config:

PowerPC 750, 192MB ram, 256MB swap, kernel 2.4.0-bitkeeper (the official
2.4 doesn't compile) + blk-13B, Adaptec 2930U, gcc 2.95.3. The rest is a
2.2.x distribution.

Bye.

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This archive was generated by hypermail 2b29 : Mon Jan 15 2001 - 21:00:37 EST