Files in procfs are always changed by kernel.
It means if we read the data with more than one read syscall,
we could get an incorrect data which was broken by kernel.
A typical case about this problem was reported by psutil in
https://github.com/giampaolo/psutil/issues/2050
Using an big buffer let read reads the whole file can fix this.
psutil uses a 32K buffer while procps-ng uses a 8K buffer, i think a 8K buffer is enough.
1. Since swap module is disabled by default, swap detection is unnecessary in most cases.
2. On platform other than Linux, swap detection doesn't share code with memory.
3. Swap detection can be expensive. On Windows, it requires another WMI query which can lag heavily in some cases. Don't pay for you don't use.
李通洲