On Mon, Jul 9, 2018 at 8:44 AM, Keith Busch keith.busch@intel.com wrote:
On Fri, Jul 06, 2018 at 03:25:15PM -0700, Dan Williams wrote:
This is going in the right direction... but still needs to account for the blk_overlap.
So, on a given DIMM BLK capacity is allocated from the top of DPA space going down and PMEM capacity is allocated from the bottom of the DPA space going up.
Since BLK capacity is single DIMM, and PMEM capacity is striped you could get into the situation where one DIMM is fully allocated for BLK usage and that would shade / remove the possibility to use the PMEM capacity on the other DIMMs in the PMEM set. PMEM needs all the same DPAs in all the DIMMs to be free.
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c index 8d348b22ba45..f30e0c3b0282 100644 --- a/drivers/nvdimm/dimm_devs.c +++ b/drivers/nvdimm/dimm_devs.c @@ -536,6 +536,31 @@ resource_size_t nd_blk_available_dpa(struct nd_region *nd_region) return info.available; }
+/**
- nd_pmem_max_contiguous_dpa - For the given dimm+region, return the max
contiguous unallocated dpa range.
- @nd_region: constrain available space check to this reference region
- @nd_mapping: container of dpa-resource-root + labels
- */
+resource_size_t nd_pmem_max_contiguous_dpa(struct nd_region *nd_region,
struct nd_mapping *nd_mapping)+{
struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);resource_size_t max = 0;struct resource *res;if (!ndd)return 0;for_each_dpa_resource(ndd, res) {if (strcmp(res->name, "pmem-reserve") != 0)continue;if (resource_size(res) > max)...so instead straight resource_size() here you need trim the end of this "pmem-reserve" resource to the start of the first BLK allocation in any of the DIMMs in the set.
See blk_start calculation in nd_pmem_available_dpa().
Hmm, the resources defining this are a bit inconvenient given these constraints. If an unallocated portion of a DIMM may only be used for BLK because an overlapping range in another DIMM is allocated that way, would it make since to insert something like a "blk-reserve" resource in all the other DIMMs so we don't need multiple iterations to calculate which DPAs can be used for PMEM?
Do you mean temporarily allocate the blk-reserve? You could have a different sized / offset BLK allocation on each DIMM in the PMEM set.