On Fri, Sep 9, 2011 at 11:45 PM, Kent Overstreet <kent.overstreet@xxxxxxxxx> wrote: > bcache, n.: a cache for arbitrary block devices that uses an SSD > > It's probably past time I started poking people to see about getting > this stuff in. It's synced up with mainline, the documentation is for > once relatively up to date, and it looks just about production ready. > > Suggestions are more than welcome on how to make it easier to review - > it's entirely too much code, I know (near 10k lines now). I'll be > emailing the patches that touch other parts of the kernel separately. > > Short overview: > Bcache does both writethrough and writeback caching. It presents itself > as a new block device, a bit like say md. You can cache an arbitrary > number of block devices with a single cache device, and attach and > detach things at runtime - it's quite flexible. > > It's very fast. It uses a b+ tree for the index, along with a journal to > coalesce index updates, and a bunch of other cool tricks like auxiliary > binary search trees with software floating point keys to avoid a bunch > of random memory accesses when doing binary searches in the btree. It > does over 50k iops doing 4k random /writes/ without breaking a sweat, > and would do many times that if I had faster hardware. Does it consider the raid5/6 write hole in what it caches? Guess I need to take a look at the code, but just wondering if it considers the need to maintain a consistent strip when writing back to raid5/6 array, or would there still be a need for a separate driver/region of the SSD for caching that data. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
