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Subject[PATCH v2 6/6] powerpc: Don't flush caches when adding memory
Date
From: Alastair D'Silva <alastair@d-silva.org>

This operation takes a significant amount of time when hotplugging
large amounts of memory (~50 seconds with 890GB of persistent memory).

This was orignally in commit fb5924fddf9e
("powerpc/mm: Flush cache on memory hot(un)plug") to support memtrace,
but the flush on add is not needed as it is flushed on remove.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
arch/powerpc/mm/mem.c | 7 -------
1 file changed, 7 deletions(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 854aaea2c6ae..2a14b5b93e19 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -111,7 +111,6 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
{
unsigned long start_pfn = start >> PAGE_SHIFT;
unsigned long nr_pages = size >> PAGE_SHIFT;
- u64 i;
int rc;

resize_hpt_for_hotplug(memblock_phys_mem_size());
@@ -124,12 +123,6 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
return -EFAULT;
}

- for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) {
- flush_dcache_range(start + i,
- min(start + size, start + i + FLUSH_CHUNK_SIZE));
- cond_resched();
- }
-
return __add_pages(nid, start_pfn, nr_pages, restrictions);
}

--
2.21.0
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