I just created a fio job file which acts like a "ls" executed while doing a large dd. It looks like the anticipatory I/O scheduler was causing those delays for me.
The results for the ls-like jobs are interesting :
I/O scheduler runt-min (msec) runt-max (msec) noop 41 10563 anticipatory 63 8185 deadline 52 33387 cfq 43 1420
Is it me or all I/O schedulers except cfq generate unexpectedly high latency ?
Details here (including fio job file) :
http://lkml.org/lkml/2009/1/18/198
Mathieu
I just created a fio job file which acts like a "ls" executed while doing a large dd. It looks like the anticipatory I/O scheduler was causing those delays for me.
The results for the ls-like jobs are interesting :
I/O scheduler runt-min (msec) runt-max (msec)
noop 41 10563
anticipatory 63 8185
deadline 52 33387
cfq 43 1420
Is it me or all I/O schedulers except cfq generate unexpectedly high latency ?
Details here (including fio job file) :
http:// lkml.org/ lkml/2009/ 1/18/198
Mathieu