Re: [PATCH 0/2] Enable ZONE_DEVICE on POWER
On 05/08/2016 11:07 PM, Aneesh Kumar K.V wrote: > oliverwrites: > >> > Hi, >> > >> > I've been working on kernel support for a persistent memory (nvdimm) >> > device and the kernel driver infrastructure requires ZONE_DEVICE for >> > DAX support.. I've had it enabled in my tree for some time (without >> > altmap support) without any real issues. > > IIUC a DAX usage of pmem doesn't really need ZONE_DEVICE. It is only > for struct page backing to those pmem area we need ZONE_DEVICE. > >> > >> > I wasn't planning on upstreaming any of my changes until 4.8 at the >> > earliest so I am ok with carrying these patches myself. However, there >> > has been some interest in using ZONE_DEVICE for other things on ppc >> > (wasn't that you?) and given that ZONE_DEVICE is gated behind >> > CONFIG_EXPERT I can't see there being any kind of negative impact on >> > end users by merging it now. At the very least it lets the rest of the >> > kernel development community know that changes affecting zones should >> > also be tested on powerpc. >> > >> > > A partially done patch like that will miss quiet a lot details. For > example if I look at the x86 changes related to altmap > (4b94ffdc4163bae1e ("x86, mm: introduce vmem_altmap to augment > vmemmap_populate")) i see them handling pagetable free and memory > hotplug. This patch doesn't do any of those. From the commit message it is > also not clear how we intent to use those zone device memory on ppc64. > If we say they will not get hotplugged out or they will never be part > of page table then those changes I mentioned above are really not > needed. But the patch is missing a lot of those details. Right. The current patch just enables ZONE_DEVICE with vmem_altmap support (so that struct pages can be allocated in the device range instead of system RAM) where any driver can own the rest of the PFNs for its use. Right now these PFNs will not make into process page table. I can update the commit message with these details if you like. ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH 0/2] Enable ZONE_DEVICE on POWER
oliverwrites: > Hi, > > I've been working on kernel support for a persistent memory (nvdimm) > device and the kernel driver infrastructure requires ZONE_DEVICE for > DAX support.. I've had it enabled in my tree for some time (without > altmap support) without any real issues. IIUC a DAX usage of pmem doesn't really need ZONE_DEVICE. It is only for struct page backing to those pmem area we need ZONE_DEVICE. > > I wasn't planning on upstreaming any of my changes until 4.8 at the > earliest so I am ok with carrying these patches myself. However, there > has been some interest in using ZONE_DEVICE for other things on ppc > (wasn't that you?) and given that ZONE_DEVICE is gated behind > CONFIG_EXPERT I can't see there being any kind of negative impact on > end users by merging it now. At the very least it lets the rest of the > kernel development community know that changes affecting zones should > also be tested on powerpc. > > A partially done patch like that will miss quiet a lot details. For example if I look at the x86 changes related to altmap (4b94ffdc4163bae1e ("x86, mm: introduce vmem_altmap to augment vmemmap_populate")) i see them handling pagetable free and memory hotplug. This patch doesn't do any of those. From the commit message it is also not clear how we intent to use those zone device memory on ppc64. If we say they will not get hotplugged out or they will never be part of page table then those changes I mentioned above are really not needed. But the patch is missing a lot of those details. -aneesh ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH 0/2] Enable ZONE_DEVICE on POWER
Hi, I've been working on kernel support for a persistent memory (nvdimm) device and the kernel driver infrastructure requires ZONE_DEVICE for DAX support.. I've had it enabled in my tree for some time (without altmap support) without any real issues. I wasn't planning on upstreaming any of my changes until 4.8 at the earliest so I am ok with carrying these patches myself. However, there has been some interest in using ZONE_DEVICE for other things on ppc (wasn't that you?) and given that ZONE_DEVICE is gated behind CONFIG_EXPERT I can't see there being any kind of negative impact on end users by merging it now. At the very least it lets the rest of the kernel development community know that changes affecting zones should also be tested on powerpc. Thanks, Oliver On Fri, May 6, 2016 at 3:13 PM, Anshuman Khandualwrote: > On 05/05/2016 08:18 PM, Aneesh Kumar K.V wrote: >> Anshuman Khandual writes: >> >>> This enables base ZONE_DEVICE support on POWER. This series depends on >>> the following patches posted by Oliver. >>> >>> https://patchwork.ozlabs.org/patch/618867/ >>> https://patchwork.ozlabs.org/patch/618868/ >>> >>> Anshuman Khandual (2): >>> powerpc/mm: Make vmemmap_populate accommodate ZONE_DEVICE memory >>> powerpc/mm: Enable support for ZONE_DEVICE on PPC_BOOK3S_64 platforms >>> >>> arch/powerpc/mm/init_64.c | 4 +++- >>> mm/Kconfig| 2 +- >>> 2 files changed, 4 insertions(+), 2 deletions(-) >>> >> >> What is the use case ? Who will use ZONE_DEVICE on ppc64. This should be >> be merged along with the patch series that use this. > > IIUC, Oliver has been looking at using ZONE_DEVICE for the NVDIMM (or > some other persistent memory) drivers. I have been following Dan William's > work on this front and want to explore more details about it's functioning > on ppc64. This enablement will just help us little bit in that direction. > ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH 0/2] Enable ZONE_DEVICE on POWER
On 05/05/2016 08:18 PM, Aneesh Kumar K.V wrote: > Anshuman Khandualwrites: > >> This enables base ZONE_DEVICE support on POWER. This series depends on >> the following patches posted by Oliver. >> >> https://patchwork.ozlabs.org/patch/618867/ >> https://patchwork.ozlabs.org/patch/618868/ >> >> Anshuman Khandual (2): >> powerpc/mm: Make vmemmap_populate accommodate ZONE_DEVICE memory >> powerpc/mm: Enable support for ZONE_DEVICE on PPC_BOOK3S_64 platforms >> >> arch/powerpc/mm/init_64.c | 4 +++- >> mm/Kconfig| 2 +- >> 2 files changed, 4 insertions(+), 2 deletions(-) >> > > What is the use case ? Who will use ZONE_DEVICE on ppc64. This should be > be merged along with the patch series that use this. IIUC, Oliver has been looking at using ZONE_DEVICE for the NVDIMM (or some other persistent memory) drivers. I have been following Dan William's work on this front and want to explore more details about it's functioning on ppc64. This enablement will just help us little bit in that direction. ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH 0/2] Enable ZONE_DEVICE on POWER
Anshuman Khandualwrites: > This enables base ZONE_DEVICE support on POWER. This series depends on > the following patches posted by Oliver. > > https://patchwork.ozlabs.org/patch/618867/ > https://patchwork.ozlabs.org/patch/618868/ > > Anshuman Khandual (2): > powerpc/mm: Make vmemmap_populate accommodate ZONE_DEVICE memory > powerpc/mm: Enable support for ZONE_DEVICE on PPC_BOOK3S_64 platforms > > arch/powerpc/mm/init_64.c | 4 +++- > mm/Kconfig| 2 +- > 2 files changed, 4 insertions(+), 2 deletions(-) > What is the use case ? Who will use ZONE_DEVICE on ppc64. This should be be merged along with the patch series that use this. -aneesh ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
[PATCH 0/2] Enable ZONE_DEVICE on POWER
This enables base ZONE_DEVICE support on POWER. This series depends on the following patches posted by Oliver. https://patchwork.ozlabs.org/patch/618867/ https://patchwork.ozlabs.org/patch/618868/ Anshuman Khandual (2): powerpc/mm: Make vmemmap_populate accommodate ZONE_DEVICE memory powerpc/mm: Enable support for ZONE_DEVICE on PPC_BOOK3S_64 platforms arch/powerpc/mm/init_64.c | 4 +++- mm/Kconfig| 2 +- 2 files changed, 4 insertions(+), 2 deletions(-) -- 1.9.3 ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev