Re: Repeat given pattern with buffer_compress_percentage

[Jens Axboe <axboe@kernel.dk>]

On 12/04/2014 12:53 AM, Karthick Srinivasachary wrote:
> Hi Jens,
>
> Thanks for your response and quick fix.. Much appreciated.
> Tried few things and saw couple issues, summarizing below. Please let
> me know if I am missing something.
>
> 1. Looks like buffer_compress_percentage with verify option is not
> giving expected compression percentage
>
> fio --name=global --rw=write --buffer_compress_percentage=50
> --name=job1 --filename=/root/test1 --size=100m --refill_buffers
> --verify=md5
>
> lz4 could compress fio data file
>
> lz4 /root/test1
> Compressed 104857600 bytes into 104857715 bytes ==> 100.00%

The verify buffers are filled differently. It will take a bit more code 
juggling to make that honor the buffer_pattern as a fill pattern. I'll 
take a look at it.

> 2. buffer_compress_percentage with buffer_pattern + refill_buffers is
> not giving expected compression percentage (Data is highly
> compressible).
>
> fio --name=global --rw=write --buffer_compress_percentage=50
> --name=job1 --filename=/root/test1 --size=100m --refill_buffers
> --buffer_pattern=111
>
> root@ubuntu-base:~/fio-master# lz4 /root/test1
> Compressed filename will be : /root/test1.lz4
> Compressed 104857600 bytes into 463065 bytes ==> 0.44%

That's a bug in how we clear refill_buffers when we set a buffer 
pattern, that's not correct anymore with the combination of buffer 
compression and pattern. Fixed and pushed.

-- 
Jens Axboe