Re: [Qemu-devel] [PATCH] block: Give always priority to unused entries in the qcow2 L2 cache

[Kevin Wolf <kwolf@redhat.com>]

Am 05.02.2015 um 13:55 hat Alberto Garcia geschrieben:
> The current algorithm to replace entries from the L2 cache gives
> priority to newer hits by dividing the hit count of all existing
> entries by two everytime there is a cache miss.
> 
> However, if there are several cache misses the hit count of the
> existing entries can easily go down to 0. This will result in those
> entries being replaced even when there are others that have never been
> used.
> 
> This problem is more noticeable with larger disk images and cache
> sizes, since the chances of having several misses before the cache is
> full are higher.
> 
> If we make sure that the hit count can never go down to 0 again,
> unused entries will always have priority.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>

Thanks, applied to the block branch.

Kevin