It's been a while since I last posted the write stream ID patchset, but here is an updated version. The original patchset was centered around the current NVMe streams proposal, but there was a number of issues with that. It's now in a much beter state, and hopefully will make it into 1.3 of the spec soon. To quickly re-summarize the intent behind write stream IDs, it's to be able to provide a hint to the underlying storage device on what writes could feasibly be grouped together. If the device is able to group writes of similar life times on media, then we can greatly reduce the amount of data that needs to be copied around at garbage collection time. This gives us a better write amplification factor, which leads to better device life times and better (and more predictable) performance at steady staet. There's been a number of changes to this patchset since it was last posted. In summary: 1) The bio parts have been bumped to carry 16 bits of stream data, up from 8 and 12 in the original series. 2) Since the interface grew some more options, I've moved away from fadvise and instead added a new system call. I don't feel strongly about what interface we use here, another option would be to have a (big) set of fcntl() commands instead. 3) The kernel now manages the ID space, since we have moved to a host assigned model. This is done on a backing_dev_info basis, and the btrfs patch has been updated to show how this can be used for nested devices on btrfs/md/dm/etc. This could be moved to the request queue as well, again I don't feel too strongly aboout this specific part. Those are the big changes. The patches are against Linus' current -git tip. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
