Hi! > The problem is we don't know the max bandwidth a disk can provide for a > specific workload, which depends on the device and IO pattern. The estimated > bandwidth by patch 1 will be always not accurate unless the disk is already in > max bandwidth. To solve this issue, we always over estimate the bandwidth. Over > esitmate bandwidth, workload dispatchs more IO, estimated bandwidth becomes > higher, dispatches even more IO. The loop will run till we enter a stable > state, in which the disk gets max bandwidth. The 'slightly adjust and run into > stable state' is the core algorithm the patch series use. We also use it to > detect inactive cgroup. Ok, so you want to reach a steady state, but what if workloads varies a lot? Lets say random writes for ten minutes, then linear write. Will the linear write be severely throttled because of the previous seeks? Can a task get bigger bandwidth by doing some additional (useless) work? Like "I do bigger reads in the random read phase, so that I'm not throttled that badly when I do the linear read"? Pavel -- 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
