Commit 438cc81a authored by David Gibson's avatar David Gibson Committed by Michael Ellerman
Browse files

powerpc/pseries: Automatically resize HPT for memory hot add/remove 



We've now implemented code in the pseries platform to use the new PAPR
interface to allow resizing the hash page table (HPT) at runtime.

This patch uses that interface to automatically attempt to resize the HPT
when memory is hot added or removed.  This tries to always keep the HPT at
a reasonable size for our current memory size.

Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 0de0fb09

arch/powerpc/include/asm/sparsemem.h

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#endif /* CONFIG_SPARSEMEM */



#ifdef CONFIG_MEMORY_HOTPLUG

extern void resize_hpt_for_hotplug(unsigned long new_mem_size);

extern int create_section_mapping(unsigned long start, unsigned long end);

extern int remove_section_mapping(unsigned long start, unsigned long end);

#ifdef CONFIG_NUMA

arch/powerpc/mm/hash_utils_64.c

+29 −0
Original line number Diff line number Diff line
@@ -749,6 +749,35 @@ static unsigned long __init htab_get_table_size(void) 
}



#ifdef CONFIG_MEMORY_HOTPLUG

void resize_hpt_for_hotplug(unsigned long new_mem_size)

{

	unsigned target_hpt_shift;



	if (!mmu_hash_ops.resize_hpt)

		return;



	target_hpt_shift = htab_shift_for_mem_size(new_mem_size);



	/*

	 * To avoid lots of HPT resizes if memory size is fluctuating

	 * across a boundary, we deliberately have some hysterisis

	 * here: we immediately increase the HPT size if the target

	 * shift exceeds the current shift, but we won't attempt to

	 * reduce unless the target shift is at least 2 below the

	 * current shift

	 */

	if ((target_hpt_shift > ppc64_pft_size)

	    || (target_hpt_shift < (ppc64_pft_size - 1))) {

		int rc;



		rc = mmu_hash_ops.resize_hpt(target_hpt_shift);

		if (rc)

			printk(KERN_WARNING

			       "Unable to resize hash page table to target order %d: %d\n",

			       target_hpt_shift, rc);

	}

}



int hash__create_section_mapping(unsigned long start, unsigned long end)

{

	int rc = htab_bolt_mapping(start, end, __pa(start),

arch/powerpc/mm/mem.c

+4 −0
Original line number Diff line number Diff line
@@ -134,6 +134,8 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) 
	unsigned long nr_pages = size >> PAGE_SHIFT;

	int rc;



	resize_hpt_for_hotplug(memblock_phys_mem_size());



	pgdata = NODE_DATA(nid);



	start = (unsigned long)__va(start);
@@ -174,6 +176,8 @@ int arch_remove_memory(u64 start, u64 size) 
	 */

	vm_unmap_aliases();



	resize_hpt_for_hotplug(memblock_phys_mem_size());



	return ret;

}

#endif

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