Re: memory caching

[Jens Axboe <jaxboe@xxxxxxxxxxxx>]

On 2011-03-15 13:36, N. Harake wrote:
> 
> I noticed when I am using --sync=1, IOPS go down to 15K and throughput to
> 53MB (That¹s horrible for the HW I am using), removing --sync I got 150K
> IOPS and almost 800MB, which make more sense. What does --sync does, and
> hope what I am doing should be enough to avoid any kind of memory caching..
> 
> Regards
> H. N. Harake
> 
> fio --name=job --directory=/lvm --size=1G --iodepth=1 --sync=1
> --filesize=1G --direct=1 --numjobs=64 --bs=4096 --rw=randwrite
> --group_reporting

If your goal is to maximize iops for testing, use the raw block device.
Use direct=1, and ioengine=libaio. Set depth large, ala:

--iodepth=128 --iodepth_batch_complete=8 --iodepth_batch_submit=8


-- 
Jens Axboe

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