Jens Axboe <axboe@xxxxxx> writes: > Hi, > > One of the things that exacerbates write amplification on flash > based devices is that fact that data with different lifetimes get > grouped together on media. Currently we have no interface that > applications can use to separate different types of writes. This > patch set adds support for that. > > The kernel has no knowledge of what stream ID is what. The idea is > that writes with identical stream IDs have similar life times, not > that stream ID 'X' has a shorter lifetime than stream ID 'X+1'. > > There are basically two interfaces that could be used for this. One > is fcntl, the other is fadvise. This patchset uses fadvise, with a > new POSIX_FADV_STREAMID hint. The 'offset' field is used to pass > the relevant stream ID. Switching to fcntl (with a SET/GET_STREAMID) > would be trivial. > > The patchset wires up the block parts, adds buffered and O_DIRECT > support, and modifies btrfs/xfs too. It should be trivial to extend > this to all other file systems, I just used xfs and btrfs for testing. > > No block drivers are wired up yet. Patches are against current -git. Can you give an idea of how the stream id would be communicated to the device? NVMe doesn't appear to have any notion of a data stream ID. Cheers, Jeff -- 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
