| Message ID | 20200501031128.19584-2-srikar@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Offline memoryless cpuless node 0 | expand |
On Fri, 1 May 2020, Srikar Dronamraju wrote: > - for_each_present_cpu(cpu) > - numa_setup_cpu(cpu); > + for_each_possible_cpu(cpu) { > + /* > + * Powerpc with CONFIG_NUMA always used to have a node 0, > + * even if it was memoryless or cpuless. For all cpus that > + * are possible but not present, cpu_to_node() would point > + * to node 0. To remove a cpuless, memoryless dummy node, > + * powerpc need to make sure all possible but not present > + * cpu_to_node are set to a proper node. > + */ > + if (cpu_present(cpu)) > + numa_setup_cpu(cpu); > + else > + set_cpu_numa_node(cpu, first_online_node); > + } > } Can this be folded into numa_setup_cpu? This looks more like numa_setup_cpu needs to change?
* Christopher Lameter <cl@linux.com> [2020-05-02 22:55:16]: > On Fri, 1 May 2020, Srikar Dronamraju wrote: > > > - for_each_present_cpu(cpu) > > - numa_setup_cpu(cpu); > > + for_each_possible_cpu(cpu) { > > + /* > > + * Powerpc with CONFIG_NUMA always used to have a node 0, > > + * even if it was memoryless or cpuless. For all cpus that > > + * are possible but not present, cpu_to_node() would point > > + * to node 0. To remove a cpuless, memoryless dummy node, > > + * powerpc need to make sure all possible but not present > > + * cpu_to_node are set to a proper node. > > + */ > > + if (cpu_present(cpu)) > > + numa_setup_cpu(cpu); > > + else > > + set_cpu_numa_node(cpu, first_online_node); > > + } > > } > > > Can this be folded into numa_setup_cpu? > > This looks more like numa_setup_cpu needs to change? > We can fold this into numa_setup_cpu(). However till now we were sure that numa_setup_cpu() would be called only for a present cpu. That assumption will change. + (non-consequential) an additional check everytime cpu is hotplugged in. If Michael Ellerman is okay with the change, I can fold it in.
Srikar Dronamraju <srikar@linux.vnet.ibm.com> writes: > * Christopher Lameter <cl@linux.com> [2020-05-02 22:55:16]: > >> On Fri, 1 May 2020, Srikar Dronamraju wrote: >> >> > - for_each_present_cpu(cpu) >> > - numa_setup_cpu(cpu); >> > + for_each_possible_cpu(cpu) { >> > + /* >> > + * Powerpc with CONFIG_NUMA always used to have a node 0, >> > + * even if it was memoryless or cpuless. For all cpus that >> > + * are possible but not present, cpu_to_node() would point >> > + * to node 0. To remove a cpuless, memoryless dummy node, >> > + * powerpc need to make sure all possible but not present >> > + * cpu_to_node are set to a proper node. >> > + */ >> > + if (cpu_present(cpu)) >> > + numa_setup_cpu(cpu); >> > + else >> > + set_cpu_numa_node(cpu, first_online_node); >> > + } >> > } >> >> Can this be folded into numa_setup_cpu? >> >> This looks more like numa_setup_cpu needs to change? > > We can fold this into numa_setup_cpu(). > > However till now we were sure that numa_setup_cpu() would be called only for > a present cpu. That assumption will change. > + (non-consequential) an additional check everytime cpu is hotplugged in. > > If Michael Ellerman is okay with the change, I can fold it in. Yes I agree it would be better in numa_setup_cpu(). cheers
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index 9fcf2d195830..b3615b7fdbdf 100644 --- a/arch/powerpc/mm/numa.c +++ b/arch/powerpc/mm/numa.c @@ -931,8 +931,20 @@ void __init mem_topology_setup(void) reset_numa_cpu_lookup_table(); - for_each_present_cpu(cpu) - numa_setup_cpu(cpu); + for_each_possible_cpu(cpu) { + /* + * Powerpc with CONFIG_NUMA always used to have a node 0, + * even if it was memoryless or cpuless. For all cpus that + * are possible but not present, cpu_to_node() would point + * to node 0. To remove a cpuless, memoryless dummy node, + * powerpc need to make sure all possible but not present + * cpu_to_node are set to a proper node. + */ + if (cpu_present(cpu)) + numa_setup_cpu(cpu); + else + set_cpu_numa_node(cpu, first_online_node); + } } void __init initmem_init(void)
A Powerpc system with multiple possible nodes and with CONFIG_NUMA enabled always used to have a node 0, even if node 0 does not any cpus or memory attached to it. As per PAPR, node affinity of a cpu is only available once its present / online. For all cpus that are possible but not present, cpu_to_node() would point to node 0. To ensure a cpuless, memoryless dummy node is not online, powerpc need to make sure all possible but not present cpu_to_node are set to a proper node. Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Cc: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Christopher Lameter <cl@linux.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> --- Changelog v1:->v2: - Rebased to v5.7-rc3 arch/powerpc/mm/numa.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)