Messages in this thread | | | Date | Fri, 01 Jul 2022 20:48:25 -0700 (PDT) | Subject | Re: [PATCH v4 0/2] use static key to optimize pgtable_l4_enabled | From | Palmer Dabbelt <> |
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On Sat, 25 Jun 2022 21:33:07 PDT (-0700), anup@brainfault.org wrote: > On Sat, May 21, 2022 at 8:13 PM Jisheng Zhang <jszhang@kernel.org> wrote: >> >> The pgtable_l4|[l5]_enabled check sits at hot code path, performance >> is impacted a lot. Since pgtable_l4|[l5]_enabled isn't changed after >> boot, so static key can be used to solve the performance issue[1]. >> >> An unified way static key was introduced in [2], but it only targets >> riscv isa extension. We dunno whether SV48 and SV57 will be considered >> as isa extension, so the unified solution isn't used for >> pgtable_l4[l5]_enabled now. >> >> patch1 fixes a NULL pointer deference if static key is used a bit earlier. >> patch2 uses the static key to optimize pgtable_l4|[l5]_enabled. >> >> [1] http://lists.infradead.org/pipermail/linux-riscv/2021-December/011164.html >> [2] https://lore.kernel.org/linux-riscv/20220517184453.3558-1-jszhang@kernel.org/T/#t >> >> Since v3: >> - fix W=1 call to undeclared function 'static_branch_likely' error >> >> Since v2: >> - move the W=1 warning fix to a separate patch >> - move the unified way to use static key to a new patch series. >> >> Since v1: >> - Add a W=1 warning fix >> - Fix W=1 error >> - Based on v5.18-rcN, since SV57 support is added, so convert >> pgtable_l5_enabled as well. >> >> >> >> Jisheng Zhang (2): >> riscv: move sbi_init() earlier before jump_label_init() >> riscv: turn pgtable_l4|[l5]_enabled to static key for RV64 > > I have tested both these patches on QEMU RV64 and RV32. > > Tested-by: Anup Patel <anup@brainfault.org> > > Thanks, > Anup
Thanks for testing these. Unfortunatly they're failing for me under my kasan+sparsemem-vmemmap config, which looks like a defconfig with
CONFIG_KASAN=y # CONFIG_FLATMEM_MANUAL is not set CONFIG_SPARSEMEM_MANUAL=y CONFIG_SPARSEMEM=y # CONFIG_SPARSEMEM_VMEMMAP is not set
Nothing's really jumping out and I'm not sure that's a super compelling configuration, but IIRC it's found a handful of issues before so I'm not sure it's sane to just toss it.
I've put this all on the riscv-pgtable_static_key branch of kernel.org/palmer/linux . If nobody has the time to look then I'll try and give it another shot, but I'm pretty buried right now so happy to have the help.
> >> >> arch/riscv/include/asm/pgalloc.h | 16 ++++---- >> arch/riscv/include/asm/pgtable-32.h | 3 ++ >> arch/riscv/include/asm/pgtable-64.h | 60 ++++++++++++++++++--------- >> arch/riscv/include/asm/pgtable.h | 5 +-- >> arch/riscv/kernel/cpu.c | 4 +- >> arch/riscv/kernel/setup.c | 2 +- >> arch/riscv/mm/init.c | 64 ++++++++++++++++++----------- >> arch/riscv/mm/kasan_init.c | 16 ++++---- >> 8 files changed, 104 insertions(+), 66 deletions(-) >> >> -- >> 2.34.1 >>
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