| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20250205151003.88959-1-ryan.roberts@arm.com> Date: Wed, 5 Feb 2025 15:09:40 +0000 From: Ryan Roberts <ryan.roberts@....com> To: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Muchun Song <muchun.song@...ux.dev>, Pasha Tatashin <pasha.tatashin@...een.com>, Andrew Morton <akpm@...ux-foundation.org>, Uladzislau Rezki <urezki@...il.com>, Christoph Hellwig <hch@...radead.org>, Mark Rutland <mark.rutland@....com>, Ard Biesheuvel <ardb@...nel.org>, Anshuman Khandual <anshuman.khandual@....com>, Dev Jain <dev.jain@....com>, Alexandre Ghiti <alexghiti@...osinc.com>, Steve Capper <steve.capper@...aro.org>, Kevin Brodsky <kevin.brodsky@....com> Cc: Ryan Roberts <ryan.roberts@....com>, linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: [PATCH v1 00/16] hugetlb and vmalloc fixes and perf improvements Hi All, This series started out as a few simple bug fixes but evolved into some code cleanups and useful performance improvements too. It mainly touches arm64 arch code but there are a couple of supporting mm changes; I'm guessing that going in through the arm64 tree is the right approach here? Beyond the bug fixes and cleanups, the 2 key performance improvements are 1) enabling the use of contpte-mapped blocks in the vmalloc space when appropriate (which reduces TLB pressure). There were already hooks for this (used by powerpc) but they required some tidying and extending for arm64. And 2) batching up barriers when modifying the vmalloc address space for upto 30% reduction in time taken in vmalloc(). vmalloc() performance was measured using the test_vmalloc.ko module. Tested on Apple M2 and Ampere Altra. Each test had loop count set to 500000 and the whole test was repeated 10 times. legend: - p: nr_pages (pages to allocate) - h: use_huge (vmalloc() vs vmalloc_huge()) - (I): statistically significant improvement (95% CI does not overlap) - (R): statistically significant regression (95% CI does not overlap) - mearements are times; smaller is better +--------------------------------------------------+-------------+-------------+ | Benchmark | | | | Result Class | Apple M2 | Ampere Alta | +==================================================+=============+=============+ | micromm/vmalloc | | | | fix_align_alloc_test: p:1, h:0 (usec) | (I) -12.93% | (I) -7.89% | | fix_size_alloc_test: p:1, h:0 (usec) | (R) 4.00% | 1.40% | | fix_size_alloc_test: p:1, h:1 (usec) | (R) 5.28% | 1.46% | | fix_size_alloc_test: p:2, h:0 (usec) | (I) -3.04% | -1.11% | | fix_size_alloc_test: p:2, h:1 (usec) | -3.24% | -2.86% | | fix_size_alloc_test: p:4, h:0 (usec) | (I) -11.77% | (I) -4.48% | | fix_size_alloc_test: p:4, h:1 (usec) | (I) -9.19% | (I) -4.45% | | fix_size_alloc_test: p:8, h:0 (usec) | (I) -19.79% | (I) -11.63% | | fix_size_alloc_test: p:8, h:1 (usec) | (I) -19.40% | (I) -11.11% | | fix_size_alloc_test: p:16, h:0 (usec) | (I) -24.89% | (I) -15.26% | | fix_size_alloc_test: p:16, h:1 (usec) | (I) -11.61% | (R) 6.00% | | fix_size_alloc_test: p:32, h:0 (usec) | (I) -26.54% | (I) -18.80% | | fix_size_alloc_test: p:32, h:1 (usec) | (I) -15.42% | (R) 5.82% | | fix_size_alloc_test: p:64, h:0 (usec) | (I) -30.25% | (I) -20.80% | | fix_size_alloc_test: p:64, h:1 (usec) | (I) -16.98% | (R) 6.54% | | fix_size_alloc_test: p:128, h:0 (usec) | (I) -32.56% | (I) -21.79% | | fix_size_alloc_test: p:128, h:1 (usec) | (I) -18.39% | (R) 5.91% | | fix_size_alloc_test: p:256, h:0 (usec) | (I) -33.33% | (I) -22.22% | | fix_size_alloc_test: p:256, h:1 (usec) | (I) -18.82% | (R) 5.79% | | fix_size_alloc_test: p:512, h:0 (usec) | (I) -33.27% | (I) -22.23% | | fix_size_alloc_test: p:512, h:1 (usec) | 0.86% | -0.71% | | full_fit_alloc_test: p:1, h:0 (usec) | 2.49% | -0.62% | | kvfree_rcu_1_arg_vmalloc_test: p:1, h:0 (usec) | 1.79% | -1.25% | | kvfree_rcu_2_arg_vmalloc_test: p:1, h:0 (usec) | -0.32% | 0.61% | | long_busy_list_alloc_test: p:1, h:0 (usec) | (I) -31.06% | (I) -19.62% | | pcpu_alloc_test: p:1, h:0 (usec) | 0.06% | 0.47% | | random_size_align_alloc_test: p:1, h:0 (usec) | (I) -14.94% | (I) -8.68% | | random_size_alloc_test: p:1, h:0 (usec) | (I) -30.22% | (I) -19.59% | | vm_map_ram_test: p:1, h:0 (usec) | 2.65% | (R) 7.22% | +--------------------------------------------------+-------------+-------------+ So there are some nice improvements but also some regressions to explain: First fix_size_alloc_test with h:1 and p:16,32,64,128,256 regress by ~6% on Altra. The regression is actually introduced by enabling contpte-mapped 64K blocks in these tests, and that regression is reduced (from about 8% if memory serves) by doing the barrier batching. I don't have a definite conclusion on the root cause, but I've ruled out the differences in the mapping paths in vmalloc. I strongly believe this is likely due to the difference in the allocation path; 64K blocks are not cached per-cpu so we have to go all the way to the buddy. I'm not sure why this doesn't show up on M2 though. Regardless, I'm going to assert that it's better to choose 16x reduction in TLB pressure vs 6% on the vmalloc allocation call duration. Next we have ~4% regression on M2 when vmalloc'ing a single page. (h is irrelevant because a single page is too small for contpte). I assume this is because there is some minor overhead in the barrier deferral mechanism and we are not getting to amortize it over multiple pages here. But I would assume vmalloc'ing 1 page is uncommon because it doesn't buy you anything over kmalloc? Applies on top of v6.14-rc1. All mm selftests run and pass. Thanks, Ryan Ryan Roberts (16): mm: hugetlb: Add huge page size param to huge_ptep_get_and_clear() arm64: hugetlb: Fix huge_ptep_get_and_clear() for non-present ptes arm64: hugetlb: Fix flush_hugetlb_tlb_range() invalidation level arm64: hugetlb: Refine tlb maintenance scope mm/page_table_check: Batch-check pmds/puds just like ptes arm64/mm: Refactor __set_ptes() and __ptep_get_and_clear() arm64: hugetlb: Use ___set_ptes() and ___ptep_get_and_clear() arm64/mm: Hoist barriers out of ___set_ptes() loop arm64/mm: Avoid barriers for invalid or userspace mappings mm/vmalloc: Warn on improper use of vunmap_range() mm/vmalloc: Gracefully unmap huge ptes arm64/mm: Support huge pte-mapped pages in vmap mm: Don't skip arch_sync_kernel_mappings() in error paths mm/vmalloc: Batch arch_sync_kernel_mappings() more efficiently mm: Generalize arch_sync_kernel_mappings() arm64/mm: Defer barriers when updating kernel mappings arch/arm64/include/asm/hugetlb.h | 33 +++- arch/arm64/include/asm/pgtable.h | 225 ++++++++++++++++++++------- arch/arm64/include/asm/thread_info.h | 2 + arch/arm64/include/asm/vmalloc.h | 40 +++++ arch/arm64/kernel/process.c | 20 ++- arch/arm64/mm/hugetlbpage.c | 114 ++++++-------- arch/loongarch/include/asm/hugetlb.h | 6 +- arch/mips/include/asm/hugetlb.h | 6 +- arch/parisc/include/asm/hugetlb.h | 2 +- arch/parisc/mm/hugetlbpage.c | 2 +- arch/powerpc/include/asm/hugetlb.h | 6 +- arch/riscv/include/asm/hugetlb.h | 3 +- arch/riscv/mm/hugetlbpage.c | 2 +- arch/s390/include/asm/hugetlb.h | 12 +- arch/s390/mm/hugetlbpage.c | 10 +- arch/sparc/include/asm/hugetlb.h | 2 +- arch/sparc/mm/hugetlbpage.c | 2 +- include/asm-generic/hugetlb.h | 2 +- include/linux/hugetlb.h | 4 +- include/linux/page_table_check.h | 30 ++-- include/linux/pgtable.h | 24 +-- include/linux/pgtable_modmask.h | 32 ++++ include/linux/vmalloc.h | 55 +++++++ mm/hugetlb.c | 4 +- mm/memory.c | 11 +- mm/page_table_check.c | 34 ++-- mm/vmalloc.c | 97 +++++++----- 27 files changed, 530 insertions(+), 250 deletions(-) create mode 100644 include/linux/pgtable_modmask.h -- 2.43.0
Powered by blists - more mailing lists