Memory usage in l4linux
adam at os.inf.tu-dresden.de
Mon Jul 25 19:16:23 CEST 2005
On Wed Jul 20, 2005 at 12:27:22 +0200, fabs0028 at free.fr wrote:
> I think other tasks directly get their memory from sigma0 with rmgr so maybe i
> should ask one of them but i don't know if it is possible and i don't know how
> to do that.
L4's memory model is hierarchical, making this a bit difficult. All
applications get their memory from sigma0. So what sigma0 could tell you
is that it gave some pages to rmgr, some others to taskx and all the
other pages to dm_phys, f.e. All other pagers will effectively tell you
the same, i.e. how many pages they gave to their clients. But that
doesn't really tell you much about the memory usage as a pager usually
doesn't use the memory it has (e.g. to store data in it) but maps it to
other tasks. One could probably argue that pages that are not mapped to
other tasks are in use by the task itself. But it's also possible to map
pages to other tasks and use this as shared memory. So this is really
just a rule of thumb, maybe.
So what you could get out of the system is the mapping tree (the kernel
know the tree) and apply the rule of thumb, for more you'd need
application knowledge, I guess.
Adam adam at os.inf.tu-dresden.de
More information about the l4-hackers