Messages in this thread | | | Date | Sun, 16 Mar 2008 11:32:00 -0700 | From | Randy Dunlap <> | Subject | Re: [RFC][3/3] Update documentation for virtual address space control |
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On Sun, 16 Mar 2008 23:00:17 +0530 Balbir Singh wrote:
> This patch adds documentation for virtual address space control. > > Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> > --- > > Documentation/controllers/memory.txt | 26 +++++++++++++++++++++++++- > 1 file changed, 25 insertions(+), 1 deletion(-) > > diff -puN Documentation/controllers/memory.txt~memory-controller-virtual-address-control-documentation Documentation/controllers/memory.txt > --- linux-2.6.25-rc5/Documentation/controllers/memory.txt~memory-controller-virtual-address-control-documentation 2008-03-16 22:57:44.000000000 +0530 > +++ linux-2.6.25-rc5-balbir/Documentation/controllers/memory.txt 2008-03-16 22:57:44.000000000 +0530 > @@ -237,7 +237,31 @@ cgroup might have some charge associated > tasks have migrated away from it. Such charges are automatically dropped at > rmdir() if there are no tasks. > > -5. TODO > +5. Virtual address space accounting > + > +A new resource counter controls the address space expansion of the tasks in > +the cgroup. Address space control is provided along the same lines as > +RLIMIT_AS control, which is available via getrlimit(2)/setrlimit(2). > +The interface for controlling address space is provided through > +"as_limit_in_bytes". The file is similar to "limit_in_bytes" w.r.t the user
w.r.t. or even spelled out.
> +interface. Please see section 3 for more details on how to use the user > +interface to get and set values. > + > +The "as_usage_in_bytes" file provides information about the total address > +space usage of the cgroup in bytes. > + > +5.1 Advantages of providing this feature > + > +1. Control over virtual address space allows for a cgroup to fail gracefully > + i.e, via a malloc or mmap failure as compared to OOM kill when no
i.e.,
> + pages can be reclaimed
end with period.
> +2. It provides better control over how many pages can be swapped out when > + the cgroup goes over it's limit. A badly setup cgroup can cause excessive
its (not "it is")
> + swapping. Providing control over the address space allocations ensures > + that the system administrator has control over the total swapping that > + can take place. > + > +6. TODO > > 1. Add support for accounting huge pages (as a separate controller) > 2. Make per-cgroup scanner reclaim not-shared pages first > _
--- ~Randy
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