Messages in this thread | | | Date | Tue, 31 Oct 2006 09:22:25 -0800 | From | "Paul Menage" <> | Subject | Re: [ckrm-tech] RFC: Memory Controller |
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On 10/31/06, Balbir Singh <balbir@in.ibm.com> wrote: > > I am still a little concerned about how limit size changes will be implemented. > Will the cpuset "mems" field change to reflect the changed limits?
That's how we've been doing it - increasing limits is easy, shrinking them is harder ...
> > Page cache control is actually more essential that RSS control, in our > > experience - it's pretty easy to track RSS values from userspace, and > > react reasonably quickly to kill things that go over their limit, but > > determining page cache usage (i.e. determining which job on the system > > is flooding the page cache with dirty buffers) is pretty much > > impossible currently. > > > > Hmm... interesting. Why do you think its impossible, what are the kinds of > issues you've run into? >
Issues such as:
- determining from userspace how much of the page cache is really "free" memory that can be given out to new jobs without impacting the performance of existing jobs
- determining which job on the system is flooding the page cache with dirty buffers
- accounting the active pagecache usage of a job as part of its memory footprint (if a process is only 1MB large but is seeking randomly through a 1GB file, treating it as only using/needing 1MB isn't practical).
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