Messages in this thread | | | Date | Tue, 12 Sep 2006 20:07:44 -0400 | From | Hubertus Franke <> | Subject | Re: [patch 1/9] Guest page hinting: unused / free pages. |
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Rik van Riel wrote: > Martin Schwidefsky wrote: > >> From: Martin Schwidefsky <schwidefsky@de.ibm.com> >> From: Hubertus Franke <frankeh@watson.ibm.com> >> From: Himanshu Raj <rhim@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
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