Re: [RFC PATCH v2 0/3] meminfo_extra: introduce meminfo extra

[Alexey Dobriyan <adobriyan@gmail.com>]

On Mon, Mar 23, 2020 at 05:05:00PM +0900, Jaewon Kim wrote:
> /proc/meminfo or show_free_areas does not show full system wide memory
> usage status because memory stats do not track all memory allocations.
> There seems to be huge hidden memory especially on embedded system. It
> is because some HW IPs in the system use common DRAM memory instead of
> internal memory. Device drivers directly request huge pages from the
> page allocator with alloc_pages.
> 
> In Android system, most of those hidden memory seems to be vmalloc
> pages, ion system heap memory, graphics memory, and memory for DRAM
> based compressed swap storage. They may be shown in other node but it
> seems to be useful if /proc/meminfo_extra shows all those extra memory
> information. And show_mem also need to print the info in oom situation.
> 
> Fortunately vmalloc pages is already shown by commit 97105f0ab7b8
> ("mm: vmalloc: show number of vmalloc pages in /proc/meminfo"). Swap
> memory using zsmalloc can be seen through vmstat by commit 91537fee0013
> ("mm: add NR_ZSMALLOC to vmstat") but not on /proc/meminfo.
> 
> Memory usage of specific driver can be various so that showing the usage
> through upstream meminfo.c is not easy. To print the extra memory usage
> of a driver, introduce following APIs. Each driver needs to count as
> atomic_long_t.
> 
> int register_meminfo_extra(atomic_long_t *val, int shift,
> 			   const char *name);
> int unregister_meminfo_extra(atomic_long_t *val);
> 
> Currently register ION system heap allocator and zsmalloc pages.
> Additionally tested on local graphics driver.
> 
> i.e) cat /proc/meminfo_extra | tail -3
> IonSystemHeap:    242620 kB
> ZsPages:          203860 kB
> GraphicDriver:    196576 kB

In that case definitely delete ':', spaces and KB.
They only slowdown generation and parsing in userspace.
Values should be printed /proc/vmstat does it, maybe with tab instead of
space.

	foo	1234
	bar	0
	zot	111