Thanks.
在 2022/6/27 14:34, Mike Rapoport 写道:
OK, I will add oneline summary in the git commit messages.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 2687275a5843Please include oneline summary of the commit. (See section "Describe your changes" in Documentation/process/submitting-patches.rst)
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 <guanghuifeng@xxxxxxxxxxxxxxxxx> --- 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
