I been running a hopefully simple fio test, but I don't understand the
results.
the test :-
fio --name=f1 --directory=/sda --rw=rw --size=400m
--name=f2 --directory=/sdb --rw=write --size=1g --startdelay=10
on linux 2.6.30-git
running this takes quite while, 'time fio ...' gives
real 3m49.174s
user 0m0.838s
sys 0m7.990s
(edited highlights of the fio output)
f1: (groupid=0, jobs=1): err= 0: pid=5181
read : io=200MiB, bw=23,480KiB/s, iops=5,870, runt= 8722msec
write: io=200MiB, bw=23,499KiB/s, iops=5,874, runt= 8715msec
f2: (groupid=0, jobs=1): err= 0: pid=5182
write: io=1,024MiB, bw=77,231KiB/s, iops=19,307, runt= 13577msec
The jobs seem to finish reasonable quickly, but then fio seem to be
stuck waiting for something. CPU usage is 100% but the CPU frequency
stays at the lowest level and the system is really sluggish in its
response. It does recover in time but this test does seem to torture my
system.
strace shows fio repeating this :-
open and read several disk stats, such as
open("/sys/block/sdb/stat", O_RDONLY) = 10
fstat(10, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff9ef70c000
read(10, " 45168 22897 2239004 1505"..., 4096) = 99
close(10) = 0
munmap(0x7ff9ef70c000, 4096) = 0
then...
gettimeofday({1245665343, 22984}, NULL) = 0
gettimeofday({1245665343, 23015}, NULL) = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
gettimeofday({1245665343, 23086}, NULL) = 0
gettimeofday({1245665343, 23115}, NULL) = 0
gettimeofday({1245665343, 23150}, NULL) = 0
setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 250000}}, NULL) = 0
rt_sigreturn(0) = -1 EINTR (Interrupted system call)
wait4(5321, 0x7fffcfed49d4, WNOHANG, NULL) = 0
nanosleep({0, 10000000}, NULL) = 0
wait4(5321, 0x7fffcfed49d4, WNOHANG, NULL) = 0
nanosleep({0, 10000000}, NULL) = 0
...
wait4(5321, 0x7fffcfed49d4, WNOHANG, NULL) = 0
nanosleep({0, 10000000}, NULL) = 0
then back to the open & reads..
The machine is a AMD X2 64bit with 3G memory & fio is 1.26.
Any ideas what's going on? or suggestions to help track it down?
thanks
Richard
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