From mboxrd@z Thu Jan 1 00:00:00 1970 From: hejianet@gmail.com (Jia He) Date: Thu, 5 Apr 2018 01:04:38 -0700 Subject: [PATCH v7 5/5] mm: page_alloc: reduce unnecessary binary search in early_pfn_valid() In-Reply-To: <1522915478-5044-1-git-send-email-hejianet@gmail.com> References: <1522915478-5044-1-git-send-email-hejianet@gmail.com> Message-ID: <1522915478-5044-6-git-send-email-hejianet@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible") optimized the loop in memmap_init_zone(). But there is still some room for improvement. E.g. in early_pfn_valid(), if pfn and pfn+1 are in the same memblock region, we can record the last returned memblock region index and check whether pfn++ is still in the same region. Currently it only improve the performance on arm/arm64 and will have no impact on other arches. For the performance improvement, after this set, I can see the time overhead of memmap_init() is reduced from 41313 us to 24345 us in my armv8a server(QDF2400 with 96G memory). Signed-off-by: Jia He --- include/linux/mmzone.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index eb56071..ab01bd3 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1271,11 +1271,16 @@ static inline int pfn_present(unsigned long pfn) #define pfn_to_nid(pfn) (0) #endif -#define early_pfn_valid(pfn) pfn_valid(pfn) #ifdef CONFIG_HAVE_ARCH_PFN_VALID extern ulong memblock_next_valid_pfn(ulong pfn); #define next_valid_pfn(pfn) memblock_next_valid_pfn(pfn) -#endif + +extern int pfn_valid_region(ulong pfn); +#define early_pfn_valid(pfn) pfn_valid_region(pfn) +#else +#define early_pfn_valid(pfn) pfn_valid(pfn) +#endif /*CONFIG_HAVE_ARCH_PFN_VALID*/ + void sparse_init(void); #else #define sparse_init() do {} while (0) -- 2.7.4