[$] The long path toward optimizing short reads

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