1) The page fault caused by the first legal writing operation on VM's legal memory area because of the violation of writing protection.
2) The page fault caused by the legal operation whose corresponding target SPT entry is empty.
In dirty pages copy phase, the page faults also need to be captured by VM monitor, which also can be achieved in the same way.
When the VM on destination resumes, the page faults will be transferred to source VM via the network and request the corresponding memory pages.
Hardware Shared Memory Cache Miss Local 11/12 Cache Miss Remote 38/38 Cache Miss 2-party 42/43 Cache Miss 3-party 63/66 Remote Software 425/707 Software Virtual Memory Distributed Array Translation 16 Pointer Translation 23 Software Shared Memory TLB Fill 2302/3590 Page Fault
11772/21956 Upgrade Fault 12441 Page Fault
, Single-Writer 29353/35293 Single-Writer Transition 9992 Release (2 writers) 33424 Release (3 writers) 33516 The second group of measurements shows the cost of software address translation.
Recording page reads and writes adds only a few instructions to the page fault
The first critical path to be tuned was the Page Fault
path, with a goal of 8,000 optimized instructions.
The table then decomposes the slowdown due to the virtualization in five categories: the time spent in the kernel, spent emulating TLB write instructions, spent emulating other privileged instructions, spent performing monitor services in the form of monitor calls or page faults
, and finally spent handling TLB misses to emulate the virtual machine's unmapped address space segments.
With the Least Recently Used (LRU) page-replacement policy, when the page size is halved, the number of page faults
can be more than double the original number of page faults
A trap is an exception that relates to a condition of a single instruction, e.g., page fault
, memory error, overflow, etc.
Sometimes can cause more page faults
when memory size is increased.