On 12/13/12 19:03, scame...@beardog.cce.hp.com wrote:
What are your system specs?
A quad core Intel i5-2400 @ 3.10 GHz.
taskset -c "$cpu" dd if="$device" of=/dev/null bs=4k iflag=direct
Please use fio instead of dd for any serious performance measurements.
dd doesn't even guarantee that it's buffers are page aligned.
I don't have "disable-frequency-scaling" on rhel6, but I think if I send
SIGUSR1 to all the cpuspeed processes, this does the same thing.
Depends on which scaling governor and minimum frequency has been
configured. This is what I am using:
#!/bin/bash
for d in /sys/devices/system/cpu/cpu*/cpufreq
do
if [ -e "$d/scaling_governor" ]; then
echo "userspace" >"$d/scaling_governor"
echo "$(<$d/cpuinfo_max_freq)" >"$d/scaling_min_freq"
fi
done
And the test I ran is:
fio --bs=4096 --ioengine=libaio --rw=randread --buffered=0 --thread \
--numjobs=${cpucount} --iodepth=16 --iodepth_batch=8 \
--iodepth_batch_complete=8 \
--loops=$((2**31)) --runtime=60 --group_reporting --size=${size} \
--gtod_reduce=1 --name=${dev} --filename=${dev} --invalidate=1
Bart.
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