Re: Time sliced CFQ io scheduler

Andrew Morton
2004-12-02T20:30:02Z

Jens Axboe <axboe@suse.de> wrote:
>
> > So what are you doing different?
>
> Doing sync io, most likely. My results above are 64k O_DIRECT reads and
> writes, see the mention of the test cases in the first mail.

OK.

Writer:

while true
do
write-and-fsync -o -m 100 -c 65536 foo
done

Reader:

time-read -o -b 65536 -n 256 x (This is O_DIRECT)
or: time-read -b 65536 -n 256 x (This is buffered)

`vmstat 1':

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 1 1032 137412 4276 84388 32 0 15456 25344 1659 1538 0 3 50 47
0 1 1032 137468 4276 84388 0 0 0 32128 1521 1027 0 2 51 48
0 1 1032 137476 4276 84388 0 0 0 32064 1519 1026 0 1 50 49
0 1 1032 137476 4276 84388 0 0 0 33920 1556 1102 0 2 50 49
0 1 1032 137476 4276 84388 0 0 0 33088 1541 1074 0 1 50 49
0 2 1032 135676 4284 85944 0 0 1656 29732 1868 2506 0 3 49 47
1 1 1032 96532 4292 125172 0 0 39220 128 10813 39313 0 31 35 34
0 2 1032 57724 4332 163892 0 0 38828 128 10716 38907 0 28 38 35
0 2 1032 18860 4368 202684 0 0 38768 128 10701 38845 1 28 38 35
0 2 1032 3672 4248 217764 0 0 39188 128 10803 39327 0 28 37 34
0 1 1032 2832 4260 218840 0 0 16812 17932 5504 17457 0 14 46 40
0 1 1032 2832 4260 218840 0 0 0 30876 1501 974 0 1 50 49
0 1 1032 2944 4260 218840 0 0 0 33472 1537 1068 0 2 50 48
0 1 1032 2944 4260 218840 0 0 0 33216 1533 1046 0 2 50 48

Ugly.

(write-and-fsync and time-read are from