hugetop: collect huge page info from /sys
There are different size of huge pages in a Linux kernel, for example, modern x86 supports both 2M and 1G huge page size. According to the latest source code, Linux support as max as 4 hstate:
struct hstate hstates[HUGE_MAX_HSTATE];
The default huge page size could be specified by kernel boot argument default_hugepagesz. Hugepagesize from /proc/meminfo shows the default hstate only. Then we hit this issue: once both 1G and 2M huge pages are in use together, /proc/meminfo only reports either one. Then part of huge pages are missing from hugetop, the huge pages number of processes may be wrong.
References: #317 (closed)
Signed-off-by: zhenwei pi pizhenwei@bytedance.com