[$] The long path toward optimizing short reads

The kernel's file-I/O subsystems have been highly optimized over the yearsin the hope of providing the best performance for a wide variety ofworkloads. There is, however, one workload type that suffers with currentkernels: applications that perform many short reads, in multiple processes,from the same file. Kiryl Shutsemau has been working on a patch totry to optimize this case, but the task is turning out to be harder thanone might expect.