Linux-Specific I/O Optimizations
Linux 2.6.17 (but the concepts were refined and interfaces altered in 2.6.18+) implemented a few new system calls for zero-copy I/O operations involving pipes: splice, tee and vmsplice
splice copies an user-specified amount data from a pipe into another pipe
tee is like splice but doesn't consume data from the input, and can be thus invoked multiple times on the same pipe
vmsplice copies data from an user-specified memory region into a pipe
Those might be useful in different cases: respectively disk cache hit, cacheable miss and (probably) error pages. We need to verify that the semantics are right, and what kind of compromises are required to implement them
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