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SubjectRe: [PATCH v2 6/6] powerpc: Don't flush caches when adding memory
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Le 03/09/2019 à 07:24, Alastair D'Silva a écrit :
> 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();
> - }
> -

So you are removing the code you added in patch 4. Why not move this one
before patch 4 ?

> return __add_pages(nid, start_pfn, nr_pages, restrictions);
> }
>
>

Christophe

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