> > The major difference between the UltraLight kernel and the stock SL > > kernel is that the SL kernel is configured with preemption enabled, > > which is great for a user desktop, but not for a high-throughput > > data server. > and is this the only difference? No. The UL kernel is built from newer sources (2.6.36), and there are a few other config tweaks, but the PREEMPT_NONE is the change that is really significant for server performace. > > We have found that on our test server (16-core server Dell 2950 with 6 > > RAID6 shelves) with the SL kernel, under load, the "ksoftirqd" daemon > so the speed benchmark is done accessing all 6 raid6 arrays or just one > raid? All 6. - Charles