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Yong Huang wrote:
>
> Quite reasonable. Now the question is, if the filesystem was created
> with a block size different than memory page size (let's not talk
> about why), iostat wsec/s divided by wrqm/s should be roughly equal to
> page size or filesystem block size?
>
>
Sorry for the delay but I prefered to test before making any statement. The answer is: "file system block size".
Today, in the lab, I could set a test environment.
(Sorry is the below steps are abvious).
I created a file system with block size 1024.
mkfs.ext3 -b 1024 /dev/sda3
mounted it
mount /dev/sda3 /mnt/test
and issued:
iostat -d -t -x /dev/sda3 5
In another shell:
dd if=/tmp/foo of=/mnt/test/foo2 bs=1024k
and here the results:
Time: 08:47:05
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz
avgqu-sz await svctm %util
/dev/sda3 0.00 0.00 2.00 0.00 4.00 0.00 2.00 0.00
2.00
0.10 50.00 50.00 1.00
Time: 08:47:10
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz
avgqu-sz await svctm %util
/dev/sda3 0.00 10200.40 0.20 83.60 0.40 20568.00 0.20
10284.00 245.
45 67.92 810.50 31.03 26.00
Let's do the usually basic math:
wsec/s / wrqm/s = 20568.00 / 10200.40 = 2,017
Roughly two sectors of 512 bytes.
So my write were in blocks of 1k.
(Note: it has nothing to do with bs=1024k in the dd command).
This thread is becoming quiet useful even for me :) I'm having fun!
-- Fabrizio Magni fabrizio.magni_at_mycontinent.com replace mycontinent with europeReceived on Mon Sep 20 2004 - 02:12:26 CDT