Messages in this thread | | | Date | Fri, 17 Jul 2009 13:33:47 +0800 | Subject | Re: [RFC patch] delete improper hot pluggable code of memory affinity | From | Luming Yu <> |
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Without a fix like my proposal, I have seen NUMA configure disabled by kernel (due to the code the patch deletes) on a system with Enabled bit set , and Hotplug-able bit cleared, and CONFIG_MEMORY_HOTPLUG_SPARSE disabled.
On Fri, Jul 17, 2009 at 1:16 PM, Yasunori Goto<y-goto@jp.fujitsu.com> wrote: > > Hi, Luming-san. > >> The current kernel code *wrongly* interprets Hot Pluggable bit of >> Memory Affinity Structure (SRAT table in ACPI spec). > > I'm not sure your patch is correct or not yet, but I would like > to tell you a critical point about the definition of > Memory Affinity Structure. > > The spec says the Enable bit of Memory Affinity Structure means that > the contents of its memory affinity structure is only VALID. > It doesn't mean memory is really connected at the area. > It means only that OS can read the entry. > > When the enabled bit and hot pluggable bit is set on, > it may mean that the area may be hot-added after boot up. > So, kernel must check e820 or efi to confirm that memory is > really connected. > > If you already know it, sorry for noise.... > Just for your information. > > Thanks. > > > >> if Hot Pluggable bit is set and CONFIG_MEMORY_HOTPLUG_SPARSE is NOT >> set, the memory Affinity will >> be ignored. And a faked Node will be used... >> >> An alternative is to enable CONFIG_MEMORY_HOTPLUG_SPARSE *always* >> along with acpi_numa_memory_affinity_init. >> Please decide which one is appropriate. >> >> The downside of this patch is *some useful info* is lost and a follow >> up patch is needed. >> >> **The patch is enclosed in text attachment* >> **Using web client to send the patch* * >> **below is for review, please apply attached patch*/ >> >> Thanks, >> Luming >> >> >> Signed-off-by: Yu Luming <luming.yu@intel.com> >> >> srat_64.c | 16 ---------------- >> 1 file changed, 16 deletions(-) >> >> >> diff --git a/arch/x86/mm/srat_64.c b/arch/x86/mm/srat_64.c >> index 2dfcbf9..82423e5 100644 >> --- a/arch/x86/mm/srat_64.c >> +++ b/arch/x86/mm/srat_64.c >> @@ -172,11 +172,6 @@ acpi_numa_processor_affinity_init(struct >> acpi_srat_cpu_affinity *pa) >> pxm, apic_id, node); >> } >> >> -#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE >> -static inline int save_add_info(void) {return 1;} >> -#else >> -static inline int save_add_info(void) {return 0;} >> -#endif >> /* >> * Update nodes_add[] >> * This code supports one contiguous hot add area per node >> @@ -249,9 +244,6 @@ acpi_numa_memory_affinity_init(struct >> acpi_srat_mem_affinity *ma) >> } >> if ((ma->flags & ACPI_SRAT_MEM_ENABLED) == 0) >> return; >> - >> - if ((ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && !save_add_info()) >> - return; >> start = ma->base_address; >> end = start + ma->length; >> pxm = ma->proximity_domain; >> @@ -291,14 +283,6 @@ acpi_numa_memory_affinity_init(struct >> acpi_srat_mem_affinity *ma) >> e820_register_active_regions(node, start >> PAGE_SHIFT, >> end >> PAGE_SHIFT); >> >> - if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) { >> - update_nodes_add(node, start, end); >> - /* restore nodes[node] */ >> - *nd = oldnode; >> - if ((nd->start | nd->end) == 0) >> - node_clear(node, nodes_parsed); >> - } >> - >> node_memblk_range[num_node_memblks].start = start; >> node_memblk_range[num_node_memblks].end = end; >> memblk_nodeid[num_node_memblks] = node; > > -- > Yasunori Goto > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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