[dm-devel] [RFC][PATCH] dm-cache: block level disk cache target for device mapper

[Ming Zhao]

On 11/30/06, Jens Wilke <jens.wilke at de.ibm.com> wrote:
>
> - You don't keep track of I/O on the fly to the cache that is mapped
> directly in cache_hit(). How do you make sure that this I/O is completed
> before you replace a cache block?


The previous I/O from cache hit and the later I/O for cache replacement
should be queued in order on the cache block device - is this a safe
assumption?


- The cache block index is hashed, this means the cache data blocks are not
> clustered. I don't think you can solve this problem with a proper hash
> function.
> Perhaps you should consider a (B-)Tree structure for that.


The current hash algorithm does clustering to some extent by mapping
consecutive blocks from the source device to consecutive blocks on the cache
device. But I agree that more sophisticated algorithms can be studied.

Thanks a lot for the suggestions. I will try to incorporate them in the next
patch.

- Ming
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