From: Hugh Dickins Date: Wed, 23 Nov 2005 21:37:37 +0000 (-0800) Subject: [PATCH] mm: update split ptlock Kconfig X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7b6ac9dffe6f4dd8776908b234ac1410ed15f112;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git [PATCH] mm: update split ptlock Kconfig Closer attention to the arithmetic shows that neither ppc64 nor sparc really uses one page for multiple page tables: how on earth could they, while pte_alloc_one returns just a struct page pointer, with no offset? Well, arm26 manages it by returning a pte_t pointer cast to a struct page pointer, harumph, then compensating in its pmd_populate. But arm26 is never SMP, so it's not a problem for split ptlock either. And the PA-RISC situation has been recently improved: CONFIG_PA20 works without the 16-byte alignment which inflated its spinlock_t. But the current union of spinlock_t with private does make the 7xxx struct page significantly larger, even without debug, so disable its split ptlock. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/Kconfig b/mm/Kconfig index ae9ce6b73e8..21eb51d4da8 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -125,12 +125,10 @@ comment "Memory hotplug is currently incompatible with Software Suspend" # space can be handled with less contention: split it at this NR_CPUS. # Default to 4 for wider testing, though 8 might be more appropriate. # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. -# PA-RISC's debug spinlock_t is too large for the 32-bit struct page. -# ARM26 and SPARC32 and PPC64 may use one page for multiple page tables. +# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. # config SPLIT_PTLOCK_CPUS int default "4096" if ARM && !CPU_CACHE_VIPT - default "4096" if PARISC && DEBUG_SPINLOCK && !64BIT - default "4096" if ARM26 || SPARC32 || PPC64 + default "4096" if PARISC && !PA20 default "4"