Hi,
it's time to pick up an old issue I discussed here earlier.
As described earlier, I'd like to extend vmstat to show the
number of allocations done per type and size, like so:
Memory statistics by type Type Kern
Type InUse MemUse HighUse Limit Requests Limit Limit Size(s)
kernfs mount 1 1K 1K 78644K 1 0 0 16:1
ptyfs mount 1 1K 1K 78644K 1 0 0 16:1
prop array 1 1K 1K 78644K 1 0 0 64:1
prop dictionary 145 19K 19K 78644K 145 0 0 128:145
prop string 143 3K 3K 78644K 143 0 0 16:143
acpi 30 1K 1K 78644K 31 0 0 16:7,32:19,64:4
USB 46 5K 5K 78644K 52 0 0 16:6,32:6,64:19,128:9,256:6,1024:0
USB device 18 19K 19K 78644K 18 0 0 16:6,128:3,2048:9
These stats are only available under KMEMSTATS, but since struct
malloc_type is part of what vmstat uses, it would not be friendly
to require a new vmstat just because you turned on KMEMSTATS in
the kernel. This means that this change will currently consume
around 5-6KB extra kernel memory. All the counting in the kernel
is however done under KMEMSTATS ifdefs.
While it is apparently true that malloc(9) over time is being
replaced by kmem(9), there remains a large number of uses of
malloc(9) in the kernel, and they are unlikely to go away anytime
soon.
This change is the first stage of a two-stage set of changes
which would make it easier to spot and trace kernel memory leaks
in use of malloc(9), and was of much help finding the kernel
memory leak documented in PRs 39145 and 42661.
The new diff is attached below. This time I've refrained from
the re-typing of the preexisting fields in "struct malloc_type",
to keep the change as small as possible.
It would appear that in addition to this change, a kernel
revision bump would be required.
Comments?
Regards,
- Håvard
