Thanks. 在 2022/6/27 14:34, Mike Rapoport 写道: > On Sun, Jun 26, 2022 at 07:10:15PM +0800, Guanghui Feng wrote: >> The arm64 can build 2M/1G block/sectiion mapping. When using DMA/DMA32 zone >> (enable crashkernel, disable rodata full, disable kfence), the mem_map will >> use non block/section mapping(for crashkernel requires to shrink the region >> in page granularity). But it will degrade performance when doing larging >> continuous mem access in kernel(memcpy/memmove, etc). >> >> There are many changes and discussions: >> commit 031495635b46 >> commit 1a8e1cef7603 >> commit 8424ecdde7df >> commit 0a30c53573b0 >> commit 2687275a5843 > Please include oneline summary of the commit. (See section "Describe your > changes" in Documentation/process/submitting-patches.rst) OK, I will add oneline summary in the git commit messages. >> This patch changes mem_map to use block/section mapping with crashkernel. >> Firstly, do block/section mapping(normally 2M or 1G) for all avail mem at >> mem_map, reserve crashkernel memory. And then walking pagetable to split >> block/section mapping to non block/section mapping(normally 4K) [[[only]]] >> for crashkernel mem. > This already happens when ZONE_DMA/ZONE_DMA32 are disabled. Please explain > why is it Ok to change the way the memory is mapped with > ZONE_DMA/ZONE_DMA32 enabled. In short: 1.building all avail mem with block/section mapping（normally 1G/2M） without inspecting crashkernel static void __init map_mem(pgd_t *pgdp) { static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN); @@ -527,17 +777,6 @@ static void __init map_mem(pgd_t *pgdp) */ memblock_mark_nomap(kernel_start, kernel_end - kernel_start); -#ifdef CONFIG_KEXEC_CORE - if (crash_mem_map) { - if (IS_ENABLED(CONFIG_ZONE_DMA) || - IS_ENABLED(CONFIG_ZONE_DMA32)) - flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; - else if (crashk_res.end) - memblock_mark_nomap(crashk_res.start, - resource_size(&crashk_res)); - } -#endif 2. Reserve crashkernel mem as same as previous doing @@ -438,8 +434,8 @@ void __init bootmem_init(void) * request_standard_resources() depends on crashkernel's memory being * reserved, so do it here. */ - if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)) - reserve_crashkernel(); + reserve_crashkernel(); + mapping_crashkernel(); 3.only change the crashkernle mem mapping to normal mapping(normally 4k). In the bootmem_init, it will reserver and remapping crashkernel to 4k pagetables by mapping_crashkernel. In the mapping_crashkernel, I will get block/section mapping interleaving with crashkernel mem，and split interleaving mapping to 4K pagetables. +void __init mapping_crashkernel(void) +{ + if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) + return; + + if (!crash_mem_map || !crashk_res.end) + return; + + map_crashkernel(swapper_pg_dir, crashk_res.start, + crashk_res.end + 1, PAGE_KERNEL, + NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); +} With this method, there are block/section mapping as more as possible. >> So the linear mem mapping use block/section mapping >> as more as possible. We will reduce the cpu dTLB miss conspicuously, and >> accelerate mem access about 10-20% performance improvement. >> >> I have tested it with pft(Page Fault Test) and fio, obtained great >> performace improvement. >> >> For fio test: >> 1.prepare ramdisk >> modprobe -r brd >> modprobe brd rd_nr=1 rd_size=67108864 >> dmsetup remove_all >> wipefs -a --force /dev/ram0 >> mkfs -t ext4 -E lazy_itable_init=0,lazy_journal_init=0 -q -F /dev/ram0 >> mkdir -p /fs/ram0 >> mount -t ext4 /dev/ram0 /fs/ram0 >> >> 2.prepare fio paremeter in x.fio file: >> [global] >> bs=4k >> ioengine=psync >> iodepth=128 >> size=32G >> direct=1 >> invalidate=1 >> group_reporting >> thread=1 >> rw=read >> directory=/fs/ram0 >> numjobs=1 >> >> [task_0] >> cpus_allowed=16 >> stonewall=1 >> >> 3.run testcase: >> perf stat -e dTLB-load-misses fio x.fio >> >> 4.contrast >> ------------------------ >> without patch with patch >> fio READ aggrb=1493.2MB/s aggrb=1775.3MB/s >> dTLB-load-misses 1,818,320,693 438,729,774 >> time elapsed(s) 70.500326434 62.877316408 >> user(s) 15.926332000 15.684721000 >> sys(s) 54.211939000 47.046165000 >> >> 5.conclusion >> Using this patch will reduce dTLB misses and improve performace greatly. >> >> Signed-off-by: Guanghui Feng >> --- >> arch/arm64/include/asm/mmu.h | 1 + >> arch/arm64/mm/init.c | 8 +- >> arch/arm64/mm/mmu.c | 274 +++++++++++++++++++++++++++++++++++++++---- >> 3 files changed, 253 insertions(+), 30 deletions(-) >> >> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h >> index 48f8466..df113cc 100644 >> --- a/arch/arm64/include/asm/mmu.h >> +++ b/arch/arm64/include/asm/mmu.h >> @@ -63,6 +63,7 @@ static inline bool arm64_kernel_unmapped_at_el0(void) >> extern void arm64_memblock_init(void); >> extern void paging_init(void); >> extern void bootmem_init(void); >> +extern void mapping_crashkernel(void); >> extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt); >> extern void init_mem_pgprot(void); >> extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >> index 339ee84..0e7540b 100644 >> --- a/arch/arm64/mm/init.c >> +++ b/arch/arm64/mm/init.c >> @@ -388,10 +388,6 @@ void __init arm64_memblock_init(void) >> } >> >> early_init_fdt_scan_reserved_mem(); >> - >> - if (!IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) >> - reserve_crashkernel(); >> - >> high_memory = __va(memblock_end_of_DRAM() - 1) + 1; >> } >> >> @@ -438,8 +434,8 @@ void __init bootmem_init(void) >> * request_standard_resources() depends on crashkernel's memory being >> * reserved, so do it here. >> */ >> - if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)) >> - reserve_crashkernel(); >> + reserve_crashkernel(); >> + mapping_crashkernel(); >> >> memblock_dump_all(); >> } >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 626ec32..0672afd 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -498,6 +498,256 @@ static int __init enable_crash_mem_map(char *arg) >> } >> early_param("crashkernel", enable_crash_mem_map); >> >> +#ifdef CONFIG_KEXEC_CORE >> +static phys_addr_t __init early_crashkernel_pgtable_alloc(int shift) >> +{ >> + phys_addr_t phys; >> + void *ptr; >> + >> + phys = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0, >> + MEMBLOCK_ALLOC_NOLEAKTRACE); >> + if (!phys) >> + panic("Failed to allocate page table page\n"); >> + >> + ptr = (void *)__phys_to_virt(phys); >> + memset(ptr, 0, PAGE_SIZE); >> + return phys; >> +} >> + >> +static void init_crashkernel_pte(pmd_t *pmdp, unsigned long addr, >> + unsigned long end, >> + phys_addr_t phys, pgprot_t prot) >> +{ >> + pte_t *ptep; >> + ptep = pte_offset_kernel(pmdp, addr); >> + do { >> + set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot)); >> + phys += PAGE_SIZE; >> + } while (ptep++, addr += PAGE_SIZE, addr != end); >> +} >> + >> +static void alloc_crashkernel_cont_pte(pmd_t *pmdp, unsigned long addr, >> + unsigned long end, phys_addr_t phys, >> + pgprot_t prot, >> + phys_addr_t (*pgtable_alloc)(int), >> + int flags) >> +{ >> + unsigned long next; >> + pmd_t pmd = READ_ONCE(*pmdp); >> + >> + BUG_ON(pmd_sect(pmd)); >> + if (pmd_none(pmd)) { >> + pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN; >> + phys_addr_t pte_phys; >> + >> + if (flags & NO_EXEC_MAPPINGS) >> + pmdval |= PMD_TABLE_PXN; >> + BUG_ON(!pgtable_alloc); >> + pte_phys = pgtable_alloc(PAGE_SHIFT); >> + __pmd_populate(pmdp, pte_phys, pmdval); >> + pmd = READ_ONCE(*pmdp); >> + } >> + BUG_ON(pmd_bad(pmd)); >> + >> + do { >> + pgprot_t __prot = prot; >> + next = pte_cont_addr_end(addr, end); >> + init_crashkernel_pte(pmdp, addr, next, phys, __prot); >> + phys += next - addr; >> + } while (addr = next, addr != end); >> +} >> + >> +static void init_crashkernel_pmd(pud_t *pudp, unsigned long addr, >> + unsigned long end, phys_addr_t phys, >> + pgprot_t prot, >> + phys_addr_t (*pgtable_alloc)(int), int flags) >> +{ >> + phys_addr_t map_offset; >> + unsigned long next; >> + pmd_t *pmdp; >> + pmdval_t pmdval; >> + >> + pmdp = pmd_offset(pudp, addr); >> + do { >> + next = pmd_addr_end(addr, end); >> + if (!pmd_none(*pmdp) && pmd_sect(*pmdp)) { >> + phys_addr_t pte_phys = pgtable_alloc(PAGE_SHIFT); >> + pmd_clear(pmdp); >> + pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN; >> + if (flags & NO_EXEC_MAPPINGS) >> + pmdval |= PMD_TABLE_PXN; >> + __pmd_populate(pmdp, pte_phys, pmdval); >> + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); >> + >> + map_offset = addr - (addr & PMD_MASK); >> + if (map_offset) >> + alloc_init_cont_pte(pmdp, addr & PMD_MASK, addr, >> + phys - map_offset, prot, >> + pgtable_alloc, flags); >> + >> + if (next < (addr & PMD_MASK) + PMD_SIZE) >> + alloc_init_cont_pte(pmdp, next, (addr & PUD_MASK) + >> + PUD_SIZE, next - addr + phys, >> + prot, pgtable_alloc, flags); >> + } >> + alloc_crashkernel_cont_pte(pmdp, addr, next, phys, prot, >> + pgtable_alloc, flags); >> + phys += next - addr; >> + } while (pmdp++, addr = next, addr != end); >> +} >> + >> +static void alloc_crashkernel_cont_pmd(pud_t *pudp, unsigned long addr, >> + unsigned long end, phys_addr_t phys, >> + pgprot_t prot, >> + phys_addr_t (*pgtable_alloc)(int), >> + int flags) >> +{ >> + unsigned long next; >> + pud_t pud = READ_ONCE(*pudp); >> + >> + /* >> + * Check for initial section mappings in the pgd/pud. >> + */ >> + BUG_ON(pud_sect(pud)); >> + if (pud_none(pud)) { >> + pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN; >> + phys_addr_t pmd_phys; >> + >> + if (flags & NO_EXEC_MAPPINGS) >> + pudval |= PUD_TABLE_PXN; >> + BUG_ON(!pgtable_alloc); >> + pmd_phys = pgtable_alloc(PMD_SHIFT); >> + __pud_populate(pudp, pmd_phys, pudval); >> + pud = READ_ONCE(*pudp); >> + } >> + BUG_ON(pud_bad(pud)); >> + >> + do { >> + pgprot_t __prot = prot; >> + next = pmd_cont_addr_end(addr, end); >> + init_crashkernel_pmd(pudp, addr, next, phys, __prot, >> + pgtable_alloc, flags); >> + phys += next - addr; >> + } while (addr = next, addr != end); >> +} >> + >> +static void alloc_crashkernel_pud(pgd_t *pgdp, unsigned long addr, >> + unsigned long end, phys_addr_t phys, >> + pgprot_t prot, >> + phys_addr_t (*pgtable_alloc)(int), >> + int flags) >> +{ >> + phys_addr_t map_offset; >> + unsigned long next; >> + pud_t *pudp; >> + p4d_t *p4dp = p4d_offset(pgdp, addr); >> + p4d_t p4d = READ_ONCE(*p4dp); >> + pudval_t pudval; >> + >> + if (p4d_none(p4d)) { >> + p4dval_t p4dval = P4D_TYPE_TABLE | P4D_TABLE_UXN; >> + phys_addr_t pud_phys; >> + >> + if (flags & NO_EXEC_MAPPINGS) >> + p4dval |= P4D_TABLE_PXN; >> + BUG_ON(!pgtable_alloc); >> + pud_phys = pgtable_alloc(PUD_SHIFT); >> + __p4d_populate(p4dp, pud_phys, p4dval); >> + p4d = READ_ONCE(*p4dp); >> + } >> + BUG_ON(p4d_bad(p4d)); >> + >> + /* >> + * No need for locking during early boot. And it doesn't work as >> + * expected with KASLR enabled. >> + */ >> + if (system_state != SYSTEM_BOOTING) >> + mutex_lock(&fixmap_lock); >> + pudp = pud_offset(p4dp, addr); >> + do { >> + next = pud_addr_end(addr, end); >> + if (!pud_none(*pudp) && pud_sect(*pudp)) { >> + phys_addr_t pmd_phys = pgtable_alloc(PMD_SHIFT); >> + pud_clear(pudp); >> + >> + pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN; >> + if (flags & NO_EXEC_MAPPINGS) >> + pudval |= PUD_TABLE_PXN; >> + __pud_populate(pudp, pmd_phys, pudval); >> + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); >> + >> + map_offset = addr - (addr & PUD_MASK); >> + if (map_offset) >> + alloc_init_cont_pmd(pudp, addr & PUD_MASK, addr, >> + phys - map_offset, prot, >> + pgtable_alloc, flags); >> + >> + if (next < (addr & PUD_MASK) + PUD_SIZE) >> + alloc_init_cont_pmd(pudp, next, (addr & PUD_MASK) + >> + PUD_SIZE, next - addr + phys, >> + prot, pgtable_alloc, flags); >> + } >> + alloc_crashkernel_cont_pmd(pudp, addr, next, phys, prot, >> + pgtable_alloc, flags); >> + phys += next - addr; >> + } while (pudp++, addr = next, addr != end); >> + >> + if (system_state != SYSTEM_BOOTING) >> + mutex_unlock(&fixmap_lock); >> +} >> + >> +static void __create_crashkernel_mapping(pgd_t *pgdir, phys_addr_t phys, >> + unsigned long virt, phys_addr_t size, >> + pgprot_t prot, >> + phys_addr_t (*pgtable_alloc)(int), >> + int flags) >> +{ >> + unsigned long addr, end, next; >> + pgd_t *pgdp = pgd_offset_pgd(pgdir, virt); >> + >> + /* >> + * If the virtual and physical address don't have the same offset >> + * within a page, we cannot map the region as the caller expects. >> + */ >> + if (WARN_ON((phys ^ virt) & ~PAGE_MASK)) >> + return; >> + >> + phys &= PAGE_MASK; >> + addr = virt & PAGE_MASK; >> + end = PAGE_ALIGN(virt + size); >> + >> + do { >> + next = pgd_addr_end(addr, end); >> + alloc_crashkernel_pud(pgdp, addr, next, phys, prot, >> + pgtable_alloc, flags); >> + phys += next - addr; >> + } while (pgdp++, addr = next, addr != end); >> +} >> + >> +static void __init map_crashkernel(pgd_t *pgdp, phys_addr_t start, >> + phys_addr_t end, pgprot_t prot, int flags) >> +{ >> + __create_crashkernel_mapping(pgdp, start, __phys_to_virt(start), >> + end - start, prot, >> + early_crashkernel_pgtable_alloc, flags); >> +} >> + >> +void __init mapping_crashkernel(void) >> +{ >> + if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) >> + return; >> + >> + if (!crash_mem_map || !crashk_res.end) >> + return; >> + >> + map_crashkernel(swapper_pg_dir, crashk_res.start, >> + crashk_res.end + 1, PAGE_KERNEL, >> + NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); >> +} >> +#else >> +void __init mapping_crashkernel(void) {} >> +#endif >> + >> static void __init map_mem(pgd_t *pgdp) >> { >> static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN); >> @@ -527,17 +777,6 @@ static void __init map_mem(pgd_t *pgdp) >> */ >> memblock_mark_nomap(kernel_start, kernel_end - kernel_start); >> >> -#ifdef CONFIG_KEXEC_CORE >> - if (crash_mem_map) { >> - if (IS_ENABLED(CONFIG_ZONE_DMA) || >> - IS_ENABLED(CONFIG_ZONE_DMA32)) >> - flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; >> - else if (crashk_res.end) >> - memblock_mark_nomap(crashk_res.start, >> - resource_size(&crashk_res)); >> - } >> -#endif >> - >> /* map all the memory banks */ >> for_each_mem_range(i, &start, &end) { >> if (start >= end) >> @@ -570,19 +809,6 @@ static void __init map_mem(pgd_t *pgdp) >> * in page granularity and put back unused memory to buddy system >> * through /sys/kernel/kexec_crash_size interface. >> */ >> -#ifdef CONFIG_KEXEC_CORE >> - if (crash_mem_map && >> - !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) { >> - if (crashk_res.end) { >> - __map_memblock(pgdp, crashk_res.start, >> - crashk_res.end + 1, >> - PAGE_KERNEL, >> - NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); >> - memblock_clear_nomap(crashk_res.start, >> - resource_size(&crashk_res)); >> - } >> - } >> -#endif >> } >> >> void mark_rodata_ro(void) >> -- >> 1.8.3.1 >>