From: "Verma, Vishal L" <vishal.l.verma@intel.com>
To: "Williams, Dan J" <dan.j.williams@intel.com>,
"ross.zwisler@linux.intel.com" <ross.zwisler@linux.intel.com>,
"oceanhehy@gmail.com" <oceanhehy@gmail.com>,
"Jiang, Dave" <dave.jiang@intel.com>
Cc: "hehy1@lenovo.com" <hehy1@lenovo.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH] libnvdimm, region_devs: stop NDD_ALIASING bit test if one test pass
Date: Thu, 30 Aug 2018 21:51:01 +0000 [thread overview]
Message-ID: <1535665860.5995.78.camel@intel.com> (raw)
In-Reply-To: <1534651288-30306-1-git-send-email-oceanhehy@gmail.com>
On Sun, 2018-08-19 at 00:01 -0400, Ocean He wrote:
> From: Ocean He <hehy1@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 <hehy1@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 01.00.00.48
> 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;
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next prev parent reply other threads:[~2018-08-30 21:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-19 4:01 [PATCH] libnvdimm, region_devs: stop NDD_ALIASING bit test if one test pass Ocean He
2018-08-30 21:51 ` Verma, Vishal L [this message]
2018-09-02 12:40 ` [External] " Ocean HY1 He
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