"It has been almost two years since LWN covered the swap prefetch patch. This work, done by Con Kolivas, is based on the idea that if a system is idle, and it has pushed user data out to swap, perhaps it should spend a little time speculatively fetching that swapped data back into any free memory that might be sitting around. Then, when some application wants that memory in the future, it will already be available and the time-consuming process of fetching it from disk can be avoided. There is a vocal set of users out there who will attest that swap prefetch has made their systems work better. Even so, the swap prefetch patch has languished in the -mm tree for almost all of those two years with no path to the mainline in sight. Con has given up on the patch (and on kernel development in general). It is an unfortunate thing when a talented and well-meaning developer runs afoul of the kernel development process and walks away. So it is worth the trouble to try to understand what went wrong."