[dm-devel] bcache performance test problem

[Kent Overstreet]

That is pretty terrible performance. If you could try digging around a
bit with perf, blktrace, etc. that'd be much appreciated - otherwise
I'll see if I can come up with some way of reproducing it as soon as I
have time. I haven't done a lot of performance testing on upstream
kernels, unfortunately.

On Wed, May 23, 2012 at 9:14 PM, Qinling <mail.qinling at huawei.com> wrote:
> Hi Kent,
>
>
>
> I have tested bcache on my platform, but the result is not good. I think
> maybe the wrong config caused it. Would you pls help me to check the config,
> or give me some advice for bcache performance testing?
>
>
>
> My SSD card is  a PCIe SSD card (about 120,000 IOPS), and I used 10GB.
>
>
>
> I have download the code from
> git://evilpiepirate.org/~kent/linux-bcache.git.
>
> The commands creating bcache is below:
>
> make-bcache –B /dev/sdb8
>
> make-bcache –C –w4k –b1M –writeback /dev/hioa5
>
>
>
> I use FIO to test the seq./random IO performance, and the result is below:
>
> write             read                    randwrite    randread
>
> bcache               10809 KB/s    164502.5 KB/s     2713 KB/s    29640 KB/s
>
> cache_hit_rate  80                  79                         94
>      92
>
>
>
>
>
> And the basic test result is:
>
> Write                   read                  randwrite             randread
>
> HDD      81211.6 KB/s       172242 KB/s     2606 KB/s             1855 KB/s
>
> SSD       250948.2 KB/s     813855 KB/s     238892.7 KB/s      657319.5 KB/s
>
>