Messages in this thread | | | Subject | Re: [PATCH v9 4/8] hugetlb: disable region_add file_region coalescing | From | Mike Kravetz <> | Date | Tue, 21 Jan 2020 09:38:29 -0800 |
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On 12/17/19 3:16 PM, Mina Almasry wrote: > A follow up patch in this series adds hugetlb cgroup uncharge info the
*nit* A follow up patch in this series adds hugetlb cgroup uncharge info to the
> file_region entries in resv->regions. The cgroup uncharge info may > differ for different regions, so they can no longer be coalesced at > region_add time. So, disable region coalescing in region_add in this > patch. > > Behavior change: > > Say a resv_map exists like this [0->1], [2->3], and [5->6]. > > Then a region_chg/add call comes in region_chg/add(f=0, t=5). > > Old code would generate resv->regions: [0->5], [5->6]. > New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], > [5->6]. > > Special care needs to be taken to handle the resv->adds_in_progress > variable correctly. In the past, only 1 region would be added for every > region_chg and region_add call. But now, each call may add multiple > regions, so we can no longer increment adds_in_progress by 1 in region_chg, > or decrement adds_in_progress by 1 after region_add or region_abort. Instead, > region_chg calls add_reservation_in_range() to count the number of regions > needed and allocates those, and that info is passed to region_add and > region_abort to decrement adds_in_progress correctly. > > We've also modified the assumption that region_add after region_chg > never fails. region_chg now pre-allocates at least 1 region for > region_add. If region_add needs more regions than region_chg has > allocated for it, then it may fail. > > Signed-off-by: Mina Almasry <almasrymina@google.com> > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Thanks for the updated comments. Still, Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
-- Mike Kravetz
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