Re: [PATCH 05/17] arch, mm: pull out allocation of NODE_DATA to generic code

Mike Rapoport
2024-07-18T07:05:57Z

On Wed, Jul 17, 2024 at 04:42:48PM +0200, David Hildenbrand wrote:
> On 16.07.24 13:13, Mike Rapoport wrote:
> > From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> >
> > Architectures that support NUMA duplicate the code that allocates
> > NODE_DATA on the node-local memory with slight variations in reporting
> > of the addresses where the memory was allocated.
> >
> > Use x86 version as the basis for the generic alloc_node_data() function
> > and call this function in architecture specific numa initialization.
> >
> > Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> > ---
>
> [...]
>
> > diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c
> > index 9208eaadf690..909f6cec3a26 100644
> > --- a/arch/mips/loongson64/numa.c
> > +++ b/arch/mips/loongson64/numa.c
> > @@ -81,12 +81,8 @@ static void __init init_topology_matrix(void)
> > static void __init node_mem_init(unsigned int node)
> > {
> > - struct pglist_data *nd;
> > unsigned long node_addrspace_offset;
> > unsigned long start_pfn, end_pfn;
> > - unsigned long nd_pa;
> > - int tnid;
> > - const size_t nd_size = roundup(sizeof(pg_data_t), SMP_CACHE_BYTES);
>
> One interesting change is that we now always round up to full pages on
> architectures where we previously rounded up to SMP_CACHE_BYTES.

On my workstation struct pglist_data take 174400, cachelines: 2725, members: 43 */

> I assume we don't really expect a significant growth in memory consumption
> that we care about, especially because most systems with many nodes also
> have quite some memory around.

With Debian kernel configuration for 6.5 struct pglist data takes 174400
bytes so the increase here is below 1%.

For NUMA systems with a lot of nodes that shouldn't be a problem.

> > -/* Allocate NODE_DATA for a node on the local memory */
> > -static void __init alloc_node_data(int nid)
> > -{
> > - const size_t nd_size = roundup(sizeof(pg_data_t), PAGE_SIZE);
> > - u64 nd_pa;
> > - void *nd;
> > - int tnid;
> > -
> > - /*
> > - * Allocate node data. Try node-local memory and then any node.
> > - * Never allocate in DMA zone.
> > - */
> > - nd_pa = memblock_phys_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
> > - if (!nd_pa) {
> > - pr_err("Cannot find %zu bytes in any node (initial node: %d)\n",
> > - nd_size, nid);
> > - return;
> > - }
> > - nd = __va(nd_pa);
> > -
> > - /* report and initialize */
> > - printk(KERN_INFO "NODE_DATA(%d) allocated [mem %#010Lx-%#010Lx]\n", nid,
> > - nd_pa, nd_pa + nd_size - 1);
> > - tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
> > - if (tnid != nid)
> > - printk(KERN_INFO " NODE_DATA(%d) on node %d\n", nid, tnid);
> > -
> > - node_data[nid] = nd;
> > - memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
> > -
> > - node_set_online(nid);
> > -}
> > -
> > /**
> > * numa_cleanup_meminfo - Cleanup a numa_meminfo
> > * @mi: numa_meminfo to clean up
> > @@ -571,6 +538,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
> > continue;
> > alloc_node_data(nid);
> > + node_set_online(nid);
> > }
>
> I can spot that we only remove a single node_set_online() call from x86.
>
> What about all the other architectures? Will there be any change in behavior
> for them? Or do we simply set the nodes online later once more?

On x86 node_set_online() was a part of alloc_node_data() and I moved it
outside so it's called right after alloc_node_data(). On other
architectures the allocation didn't include that call, so there should be
no difference there.

> --
> Cheers,
>
> David / dhildenb
>
>

--
Sincerely yours,
Mike.