From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id D758B21107857 for ; Thu, 30 Aug 2018 14:55:25 -0700 (PDT) From: "Verma, Vishal L" Subject: Re: [PATCH] libnvdimm, region_devs: stop NDD_ALIASING bit test if one test pass Date: Thu, 30 Aug 2018 21:51:01 +0000 Message-ID: <1535665860.5995.78.camel@intel.com> References: <1534651288-30306-1-git-send-email-oceanhehy@gmail.com> In-Reply-To: <1534651288-30306-1-git-send-email-oceanhehy@gmail.com> Content-Language: en-US Content-ID: MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: "Williams, Dan J" , "ross.zwisler@linux.intel.com" , "oceanhehy@gmail.com" , "Jiang, Dave" Cc: "hehy1@lenovo.com" , "linux-kernel@vger.kernel.org" , "linux-nvdimm@lists.01.org" List-ID: On Sun, 2018-08-19 at 00:01 -0400, Ocean He wrote: > From: Ocean He > > 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 > --- > 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 01.00.00.48 > 88 > 0x0121 125.7 > GiB Healthy 0 Disabled 01.00.00.48 > 88 > 0x1021 125.7 > GiB Healthy 0 Disabled 01.00.00.48 > 88 > 0x1121 125.7 > GiB Healthy 0 Disabled 01.00.00.48 > 88 > > # 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; I think we can go a step further, and instead of the 'break' followed by a check for the 'alias' variable, in the loop, just return ND_DEVICE_NAMESPACE_PMEM if the NDD_ALIASING bit is found for any mapping. Outside the loop, simply return ND_DEVICE_NAMESPACE_IO. That makes it much cleaner and now we can get rid of 'alias' entirely. > + } > } > if (alias) > return ND_DEVICE_NAMESPACE_PMEM; _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm