Flash based storage has its characteristics. CFQ has some optimizations for it, but not enough. The big problem is CFQ doesn't drive deep queue depth, which causes poor performance in some workloads. CFQ also isn't quite fair for fast storage (or further sacrifice of performance to get fairness) because it uses time based accounting. This isn't good for block cgroup. We need something different to make both performance and fairness good. A recent attempt is to use IOPS based ioscheduler for flash based storage. It's expected to drive deep queue depth (so better performance) and be more fairness (IOPS based accounting instead of time based). I'd like to discuss: - Do we really need it? Or the question is if it is popular real workloads drive deep io depth? - Should we have a separate ioscheduler for this or merge it to CFQ? - Other implementation discussions like differentiation of read/write requests and request size. Flash based storage doesn't like rotate storage, request cost of read/write and different request size usually is different. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
