Rik van Riel wrote: > Martin Schwidefsky wrote: > >> From: Martin Schwidefsky <schwidefsky at de.ibm.com> >> From: Hubertus Franke <frankeh at watson.ibm.com> >> From: Himanshu Raj <rhim at cc.gatech.edu> >> >> [patch 1/9] Guest page hinting: unused / free pages. >> >> A very simple but already quite effective improvement in the handling >> of guest memory vs. host memory is to tell the host when pages are >> free. > > > Would it be an idea to place this interface in-between the > per-cpu free page lists and the buddy allocator, so we can > move a batch of pages around at once and do the hinting in > a batched fashion ? > > That way the overhead will be acceptable not just on S390 > (where things are millicoded), but also on hypervisor based > virtualization like Xen. > > Easy enough to pass a vector of pages to the hypervisor. > Rik, I thought that what we did. Martin, I see the code actually does it when the page goes into the hot/cold list. I can't remember conciously moving to that. I thought we had a decent hit on the hot/cold, so that bulking makes sense. Then the interface of bulking could be introduced and for s390 it could internally be implemented as a sequence of ESSA instruction. Do you remember the reason why we ended up putting it as part of hot/cold freeing? -- Hubertus
