On 22.05.2019 18:52, Michal Hocko wrote:
On Wed 22-05-19 17:40:09, Konstantin Khlebnikov wrote:
Some kinds of kernel allocations are not accounted or not show in meminfo.
For example vmalloc allocations are tracked but overall size is not shown
for performance reasons. There is no information about network buffers.
In most cases detailed statistics is not required. At first place we need
information about overall kernel memory usage regardless of its structure.
This patch estimates kernel memory usage by subtracting known sizes of
free, anonymous, hugetlb and caches from total memory size: MemKernel =
MemTotal - MemFree - Buffers - Cached - SwapCached - AnonPages - Hugetlb.
Why do we need to export something that can be calculated in the
userspace trivially? Also is this really something the number really
meaningful? Say you have a driver that exports memory to the userspace
via mmap but that memory is not accounted. Is this really a kernel
memory?
It may be trivial right now but not fixed.
Adding new kinds of memory may change this definition.
For example hypothetical 'GPU buffers' may be handled as 'userspace' memory.
