Xunlei Pang 66aad4fdf2 x86/mm: Add support for gbpages to kernel_ident_mapping_init() ... Kernel identity mappings on x86-64 kernels are created in two ways: by the early x86 boot code, or by kernel_ident_mapping_init(). Native kernels (which is the dominant usecase) use the former, but the kexec and the hibernation code uses kernel_ident_mapping_init(). There's a subtle difference between these two ways of how identity mappings are created, the current kernel_ident_mapping_init() code creates identity mappings always using 2MB page(PMD level) - while the native kernel boot path also utilizes gbpages where available. This difference is suboptimal both for performance and for memory usage: kernel_ident_mapping_init() needs to allocate pages for the page tables when creating the new identity mappings. This patch adds 1GB page(PUD level) support to kernel_ident_mapping_init() to address these concerns. The primary advantage would be better TLB coverage/performance, because we'd utilize 1GB TLBs instead of 2MB ones. It is also useful for machines with large number of memory to save paging structure allocations(around 4MB/TB using 2MB page) when setting identity mappings for all the memory, after using 1GB page it will consume only 8KB/TB. ( Note that this change alone does not activate gbpages in kexec, we are doing that in a separate patch. ) Signed-off-by: Xunlei Pang <xlpang@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Young <dyoung@redhat.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yinghai Lu <yinghai@kernel.org> Cc: akpm@linux-foundation.org Cc: kexec@lists.infradead.org Link: http://lkml.kernel.org/r/1493862171-8799-1-git-send-email-xlpang@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2017-05-08 08:28:40 +02:00
..
cpu.c	x86: Remap GDT tables in the fixmap section	2017-03-16 09:06:35 +01:00
hibernate_32.c	x86/mm: Convert trivial cases of page table walk to 5-level paging	2017-03-14 08:45:08 +01:00
hibernate_64.c	x86/mm: Add support for gbpages to kernel_ident_mapping_init()	2017-05-08 08:28:40 +02:00
hibernate_asm_32.S	x86, gdt, hibernate: Store/load GDT for hibernate path.	2013-05-02 11:27:35 -07:00
hibernate_asm_64.S	x86/power/64: Do not refer to __PAGE_OFFSET from assembly code	2016-08-03 01:35:38 +02:00
Makefile