Messages in this thread |  | | Subject | Re: broken VM in 2.4.10-pre9 | From | (Eric W. Biederman) | Date | 17 Sep 2001 02:06:46 -0600 |
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Rik van Riel <riel@conectiva.com.br> writes:
> On 16 Sep 2001, Michael Rothwell wrote: > > > Is there a way to tell the VM to prune its cache? Or a way to limit > > the amount of cache it uses? > > Not yet, I'll make a quick hack for this when I get back next > week. It's pretty obvious now that the 2.4 kernel cannot get > enough information to select the right pages to evict from > memory.
Hmm. Perhaps or perhaps it is using the information poorly. There is an alternative approach to have better aging information.
An address_space can be allocated per mm_struct. And all of the anonymous pages can be allocated to that address_space. The address_space can then have an array or better a tree of extents that list which indexes correspond to which swap pages. With some pages not being backed.
Getting the allocation of indices correct so that merging will work is a little trickier then now, as is the case of a private writeable mapping of a file. But in a lot of other ways the logic becomes simpler.
> For 2.5 I'm making a VM subsystem with reverse mappings, the > first iterations are giving very sweet performance so I will > continue with this project regardless of what other kernel > hackers might say ;)
Do you have any arguments for the reverse mappings or just for some of the other side effects that go along with them?
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