On Tue, 2022-01-11 at 09:39 -0800, Dave Hansen wrote: > On 1/11/22 08:33, Haitao Huang wrote: > > On Tue, 11 Jan 2022 09:43:35 -0600, Dave Hansen < > > dave.hansen@xxxxxxxxx> > > wrote: > > > On 1/11/22 06:20, Haitao Huang wrote: > > > > If the system has a ton of RAM but limited EPC, I think it > > > > makes > > > > sense to allow more EPC swapping, can we do min(0.5*RAM, > > > > 2*EPC)? > > > > I suppose if the system is used for heavy enclave load, user > > > > would be > > > > willing to at least use half of RAM. > > > > > > If I have 100GB of RAM and 100MB of EPC, can I really > > > *meaningfully* > > > run 50GB of enclaves? In that case, if everything was swapped > > > out > > > evenly, I would only have a 499/500 chance that a given page > > > reference > > > would fault. > > > > The formula will cap swapping at 2*EPC so only 200MB swapped out. > > So > > the miss is at most 1/3. > > The original hard coded cap 1.5*EPC may still consume too much RAM > > if > > RAM<1.5*EPC. > > Oh, sorry, I read that backwards. > > Basing it on the amount of RAM is a bit nasty. You might either > really > overly restrict the amount of allowed EPC, or you have to handle > hotplug. My opinion is that we should keep the current algorithm for now as it is pretty straightforward, and cgroups will eventually allow for more control.
