Re: [PATCH v7 07/11] sparc64: optimized struct page zeroing
From: David Miller
Date: Tue Aug 29 2017 - 21:12:17 EST
From: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Date: Mon, 28 Aug 2017 22:02:18 -0400
> Add an optimized mm_zero_struct_page(), so struct page's are zeroed without
> calling memset(). We do eight to ten regular stores based on the size of
> struct page. Compiler optimizes out the conditions of switch() statement.
>
> SPARC-M6 with 15T of memory, single thread performance:
>
> BASE FIX OPTIMIZED_FIX
> bootmem_init 28.440467985s 2.305674818s 2.305161615s
> free_area_init_nodes 202.845901673s 225.343084508s 172.556506560s
> --------------------------------------------
> Total 231.286369658s 227.648759326s 174.861668175s
>
> BASE: current linux
> FIX: This patch series without "optimized struct page zeroing"
> OPTIMIZED_FIX: This patch series including the current patch.
>
> bootmem_init() is where memory for struct pages is zeroed during
> allocation. Note, about two seconds in this function is a fixed time: it
> does not increase as memory is increased.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> Reviewed-by: Steven Sistare <steven.sistare@xxxxxxxxxx>
> Reviewed-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
> Reviewed-by: Bob Picco <bob.picco@xxxxxxxxxx>
You should probably use initializing stores when you are doing 8
stores and we thus know the page struct is cache line aligned.
But other than that:
Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>