On 2014-09-24 15:22, Sitsofe Wheeler wrote:
(Adding Jens to the CC list)
On 24 September 2014 10:52, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote:
On 24 September 2014 09:35, Akira Hayakawa <ruby.wktk@xxxxxxxxx> wrote:
However, I [...] think I still have a problem.
I modified the command
From:
fio --name=test --filename=#{dev.path} --rw=write --ioengine=libaio --direct=1 --io_limit=32M --size=100% --ba=4k --bs=512
To:
fio --name=test --filename=#{dev.path} --rw=write:4k --ioengine=libaio --direct=1 --io_limit=32M --bs=512
The result is the runtime is too short.
This looks like a bug. I can reproduce it with 2.1.11-11-gb7f5 too:
dd if=/dev/zero of=/dev/shm/1M bs=1M count=1
fio --bs=4k --rw=write:4k --filename=/dev/shm/1M --stonewall --name=1M
--io_limit=1M --name=2M --io_limit=2M
[...]
Run status group 0 (all jobs):
WRITE: io=512KB, aggrb=256000KB/s, minb=256000KB/s, maxb=256000KB/s,
mint=2msec, maxt=2msec
Run status group 1 (all jobs):
WRITE: io=512KB, aggrb=256000KB/s, minb=256000KB/s, maxb=256000KB/s,
mint=2msec, maxt=2msec
Why isn't io 1024KB for group 0? Additionally, shouldn't the total io
written each group be different? Jens?
You are doing a sequential workload, skipping 4k every time. First write
will be to offset 0, next to 8KB, etc. Write 128 would be to 1040384,
which is 1MB - 8KB. Hence the next feasible offset after that would be
1MB, which is end of the file. So how could it do more than 512KB of IO?
That's 128 * 4KB.
I didn't read the whole thread in detail, just looked at your last
example here. And for that one, I don't see anything wrong.
--
Jens Axboe
--
To unsubscribe from this list: send the line "unsubscribe fio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
