6aa26565e6
- to isolate execution inside kernel we use a big kernel lock implemented as a spinlock - the lock is acquired asap after entering kernel mode and released as late as possible. Only one CPU as a time can execute the core kernel code - measurement son real hw show that the overhead of this lock is close to 0% of kernel time for the currnet system - the overhead of this lock may be as high as 45% of kernel time in virtual machines depending on the ratio between physical CPUs available and emulated CPUs. The performance degradation is significant