From: Ocean He <he...@lenovo.com> There is no need to finish entire loop to execute NDD_ALIASING bit test against every nvdimm->flags. In practice, all the nd_mapping->nvdimm have the same flags.
Because the check of alias is "if (alias)" but not "if (alias == nd_region->ndr_mappings)", there is no function change while just save a few cycles. Signed-off-by: Ocean He <he...@lenovo.com> --- A test to check if all the nd_mapping->nvdimm have the same flags, using Lenovo ThinkSystem SR630 and 4.18-rc6. # ipmctl show -dimm DimmID Capacity HealthState ActionRequired LockState FWVersion 0x0021 125.7 GiB Healthy 0 Disabled 01.00.00.4888 0x0121 125.7 GiB Healthy 0 Disabled 01.00.00.4888 0x1021 125.7 GiB Healthy 0 Disabled 01.00.00.4888 0x1121 125.7 GiB Healthy 0 Disabled 01.00.00.4888 # ipmctl create -f -goal -socket 0x0 PersistentMemoryType=AppDirect # ipmctl create -f -goal -socket 0x1 PersistentMemoryType=AppDirect # reboot, to make goal configuration take effect. # ndctl create-namespace -r region0 -s 100m -t pmem -m fsdax # ndctl create-namespace -r region1 -s 100m -t pmem -m fsdax # reboot and find all the nd_mapping->nvdimm have the same flags. drivers/nvdimm/region_devs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index ec3543b..fc3bc1c 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -234,8 +234,10 @@ int nd_region_to_nstype(struct nd_region *nd_region) struct nd_mapping *nd_mapping = &nd_region->mapping[i]; struct nvdimm *nvdimm = nd_mapping->nvdimm; - if (test_bit(NDD_ALIASING, &nvdimm->flags)) + if (test_bit(NDD_ALIASING, &nvdimm->flags)) { alias++; + break; + } } if (alias) return ND_DEVICE_NAMESPACE_PMEM; -- 1.8.3.1 _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm