The Design and Implementation of the Anykernel and Rump Kernels

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2CPU
native rump old rump new
Figure 3.8: System call performance using the improved CPU scheduler.
The advanced rump kernel CPU scheduler is lockless and cache conscious. With it,
simultaneous system calls from multiple threads are over twice as fast as against the
host kernel and over four times as fast as with the old scheduler.
Performance
The impact of the improved CPU scheduling algorithm is shown in Figure 3.8. The
new algorithm performs four times as good as the freelist algorithm in the dual CPU
multithreaded case. It also performs twice as fast as a host kernel system call. Also,
there is scalability: the dual CPU case is within 1% of the performance of the single
CPU case — native performance is 20% weaker with two CPUs. Finally, the jitter
we set out to eliminate has been eliminated.
CPU-bound lwps
A CPU-bound lwp will execute only on a specific CPU. This functionality is required
for example for delivering a clock interrupt on every virtual CPU. Any lwp which