Occlum is a single-address-space library OS. Previously, userspace memory are divided for each process.
And all the memory are allocated when the process is created, which leads to a lot of wasted space and
complicated configuration.
In the current implementation, the whole userspace is managed as a memory pool that consists of chunks. There
are two kinds of chunks:
(1) Single VMA chunk: a chunk with only one VMA. Should be owned by exactly one process.
(2) Multi VMA chunk: a chunk with default chunk size and there could be a lot of VMAs in this chunk. Can be used
by different processes.
This design can help to achieve mainly two goals:
(1) Simplify the configuration: Users don't need to configure the process.default_mmap_size anymore. And multiple processes
running in the same Occlum instance can use dramatically different sizes of memory.
(2) Gain better performance: Two-level management(chunks & VMAs) reduces the time for finding, inserting, deleting, and iterating.
1. Add OCCLUM_COV to conditionally enable gcov profiling for libos Rust
code;
2. Add a makefile target to locally generate the coverage report in html
format.
1. Implement type-safe functions;
2. Improve the correctness of nearly all the functions;
3. Improve the readability by introducing Listener and Endpoint for StreamUnix;
4. Substitue RingBuf with Channel in Unix socket.
1. Introduce channels, which provide an efficient means for IPC;
2. Leverage channels to rewrite pipe, improving the performance (3X),
robustness, and readability.
This pipe rewrite is not done: some more commits will be added to
implement poll and epoll for pipe.
