[dm-devel] Thinly-Provisioned Logical Volumes

[Mike Snitzer]

On Sat, Sep 20 2014 at 10:19am -0400,
lilofile <lilofile at aliyun.com> wrote:

> when I test Thinly-Provisioned Logical Volumes(use device thinprovison
> target),I found the random write performance is very low. What factors
> will influence the random write performance of  thin volume.

It is worth reading this blog post from Joe:
http://device-mapper.org/blog/2014/01/21/random-io-and-copy-on-write-schemes/

> how can i quickly understand dm-bufio.c?

What is it you'd like to know?  dm-bufio.c isn't the smoking gun for
random write performance being slow though.  It is more to do with the
natural impact random writes have on thinp (as discussed in the above
article).