Yes, you are absolutely right about that. I think it would be good to include the map time (even though called it once) for completeness :).
On Mon, May 1, 2017 at 10:36 PM, <[email protected]> wrote: > Hi Oak, > > My understanding is that in your use case, the map is a one-off and > therefore not performance-critical, while the re-map needs to be done on > each snapshot and therefore is performance-critical. > > I hope the student gets to evaluate alternative implementation so we can > see how much benefit bulk operations would provide. > > Gernot > > On 2 May 2017, at 15:32 , Norrathep Rattanavipanon <[email protected]> > wrote: > > Hi Adrain and Gernot, > > Thank you for the clarification. Yes, sorry, forgot to mention that we are > using ARM i.MX6 Sabre Lite and forgot to mention some backgrounds. > > We are interested in benchmarking (1) the time to lock large memory > regions (switching from R/W to R/O) and (2) the time to map large memory > regions as Gernot mentioned its for providing a consistent snapshot of user > memory. > So just to make sure the current implementation for that is the optimal > remap (modify paging structure, clean cache, invalidate tlb), correct? > > @Gernot, right, per our discussion, we only discussed out a bulk mapping > operation (mapping from other processes into the root process) but I was > not sure about locking (which is remapping in this case). Thank you for > confirming. > > Best, > Oak > > On Mon, May 1, 2017 at 10:18 PM, <[email protected]> wrote: > >> On 2 May 2017, at 3:21 , Norrathep Rattanavipanon <[email protected]> >> wrote: >> >> >> 2) If my understanding in 1) is correct, the remap function only takes 1 >> cap at a time. >> So if I want to modify access rights of many pages, do I have to call the >> remap function multiple times? >> Or is there a more efficient way to do so? >> >> >> Hi Oak, >> >> As we discussed in person, this is a known issue of our API, and I have >> presently a student doing some evaluations. I have your use case in mind >> when talking to the student – for everyone else’s benefit, this is about a >> consistent shapshot of user memory for doing remote attestation. >> >> I would be interested in other use cases for a bulk re-mapping operation. >> I suspect that there are use cases where this might be a bottleneck, but it >> would be good to identify specific cases of enough significance to consider >> an API change. Certainly there won’t be a change if we don’t have >> convincing use cases. >> >> Gernot >> > > > > -- > Norrathep (Oak) Rattanavipanon > M.S. in Computer Science > University of California - Irvine > > > -- Norrathep (Oak) Rattanavipanon M.S. in Computer Science University of California - Irvine
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