Re: [Qemu-devel] [PATCH v8 0/8] Take the image size into account when allocating the L2 cache

[Kevin Wolf]

Hi Leonid,

Am 13.08.2018 um 03:07 hat Leonid Bloch geschrieben:
> This series makes the qcow2 L2 cache assignment aware of the image size,
> with the intention for it to cover the entire image. The importance of
> this change is in noticeable performance improvement, especially with
> heavy random I/O. The memory overhead is not big in most cases, as only
> 1 MB of cache for every 8 GB of image size is used. For cases with very
> large images and/or small cluster sizes, or systems with limited RAM
> resources, there is an upper limit on the default L2 cache: 32 MB. To
> modify this limit one can use the already existing 'l2-cache-size' and
> 'cache-size' options. Moreover, this fixes the behavior of 'l2-cache-size',
> as it was documented as the *maximum* L2 cache size, but in practice
> behaved as the absolute size.
> 
> To compensate the memory overhead which may be increased following this
> behavior, the default cache-clean-interval is set to 10 minutes by default
> (was disabled by default before).
> 
> The L2 cache is also resized accordingly, by default, if the image is
> resized.

after digging through the most urgent part of my post-vacation backlog,
I saw this series again. It's been a while, but I don't think much is
missing, so let's get this finished now. :-)

We had some discussion in the v7 thread after you posted v8, and you
mentioned there that you'd do some changes in a v9 (at first sight, just
some test case stuff). Are you still planning to send that v9?

Kevin