Messages in this thread | | | Date | Tue, 9 Apr 2024 11:04:46 +0100 | Subject | Re: [PATCH v2 0/4] Speed up boot with faster linear map creation | From | Ryan Roberts <> |
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On 09/04/2024 01:10, Itaru Kitayama wrote: > Hi Ryan, > >> On Apr 8, 2024, at 16:30, Ryan Roberts <ryan.roberts@arm.com> wrote: >> >> On 06/04/2024 11:31, Itaru Kitayama wrote: >>> Hi Ryan, >>> >>> On Sat, Apr 06, 2024 at 09:32:34AM +0100, Ryan Roberts wrote: >>>> Hi Itaru, >>>> >>>> On 05/04/2024 08:39, Itaru Kitayama wrote: >>>>> On Thu, Apr 04, 2024 at 03:33:04PM +0100, Ryan Roberts wrote: >>>>>> Hi All, >>>>>> >>>>>> It turns out that creating the linear map can take a significant proportion of >>>>>> the total boot time, especially when rodata=full. And most of the time is spent >>>>>> waiting on superfluous tlb invalidation and memory barriers. This series reworks >>>>>> the kernel pgtable generation code to significantly reduce the number of those >>>>>> TLBIs, ISBs and DSBs. See each patch for details. >>>>>> >>>>>> The below shows the execution time of map_mem() across a couple of different >>>>>> systems with different RAM configurations. We measure after applying each patch >>>>>> and show the improvement relative to base (v6.9-rc2): >>>>>> >>>>>> | Apple M2 VM | Ampere Altra| Ampere Altra| Ampere Altra >>>>>> | VM, 16G | VM, 64G | VM, 256G | Metal, 512G >>>>>> ---------------|-------------|-------------|-------------|------------- >>>>>> | ms (%) | ms (%) | ms (%) | ms (%) >>>>>> ---------------|-------------|-------------|-------------|------------- >>>>>> base | 153 (0%) | 2227 (0%) | 8798 (0%) | 17442 (0%) >>>>>> no-cont-remap | 77 (-49%) | 431 (-81%) | 1727 (-80%) | 3796 (-78%) >>>>>> batch-barriers | 13 (-92%) | 162 (-93%) | 655 (-93%) | 1656 (-91%) >>>>>> no-alloc-remap | 11 (-93%) | 109 (-95%) | 449 (-95%) | 1257 (-93%) >>>>>> lazy-unmap | 6 (-96%) | 61 (-97%) | 257 (-97%) | 838 (-95%) >>>>>> >>>>>> This series applies on top of v6.9-rc2. All mm selftests pass. I've compile and >>>>>> boot tested various PAGE_SIZE and VA size configs. >>>>>> >>>>>> --- >>>>>> >>>>>> Changes since v1 [1] >>>>>> ==================== >>>>>> >>>>>> - Added Tested-by tags (thanks to Eric and Itaru) >>>>>> - Renamed ___set_pte() -> __set_pte_nosync() (per Ard) >>>>>> - Reordered patches (biggest impact & least controversial first) >>>>>> - Reordered alloc/map/unmap functions in mmu.c to aid reader >>>>>> - pte_clear() -> __pte_clear() in clear_fixmap_nosync() >>>>>> - Reverted generic p4d_index() which caused x86 build error. Replaced with >>>>>> unconditional p4d_index() define under arm64. >>>>>> >>>>>> >>>>>> [1] https://lore.kernel.org/linux-arm-kernel/20240326101448.3453626-1-ryan.roberts@arm.com/ <https://lore.kernel.org/linux-arm-kernel/20240326101448.3453626-1-ryan.roberts@arm.com/> >>>>>> >>>>>> Thanks, >>>>>> Ryan >>>>>> >>>>>> >>>>>> Ryan Roberts (4): >>>>>> arm64: mm: Don't remap pgtables per-cont(pte|pmd) block >>>>>> arm64: mm: Batch dsb and isb when populating pgtables >>>>>> arm64: mm: Don't remap pgtables for allocate vs populate >>>>>> arm64: mm: Lazily clear pte table mappings from fixmap >>>>>> >>>>>> arch/arm64/include/asm/fixmap.h | 5 +- >>>>>> arch/arm64/include/asm/mmu.h | 8 + >>>>>> arch/arm64/include/asm/pgtable.h | 13 +- >>>>>> arch/arm64/kernel/cpufeature.c | 10 +- >>>>>> arch/arm64/mm/fixmap.c | 11 + >>>>>> arch/arm64/mm/mmu.c | 377 +++++++++++++++++++++++-------- >>>>>> 6 files changed, 319 insertions(+), 105 deletions(-) >>>>>> >>>>>> -- >>>>>> 2.25.1 >>>>>> >>>>> >>>>> I've build and boot tested the v2 on FVP, base is taken from your >>>>> linux-rr repo. Running run_vmtests.sh on v2 left some gup longterm not oks, would you take a look at it? The mm ksefltests used is from your linux-rr repo too. >>>> >>>> Thanks for taking a look at this. >>>> >>>> I can't reproduce your issue unfortunately; steps as follows on Apple M2 VM: >>>> >>>> Config: arm64 defconfig + the following: >>>> >>>> # Squashfs for snaps, xfs for large file folios. >>>> ./scripts/config --enable CONFIG_SQUASHFS_LZ4 >>>> ./scripts/config --enable CONFIG_SQUASHFS_LZO >>>> ./scripts/config --enable CONFIG_SQUASHFS_XZ >>>> ./scripts/config --enable CONFIG_SQUASHFS_ZSTD >>>> ./scripts/config --enable CONFIG_XFS_FS >>>> >>>> # For general mm debug. >>>> ./scripts/config --enable CONFIG_DEBUG_VM >>>> ./scripts/config --enable CONFIG_DEBUG_VM_MAPLE_TREE >>>> ./scripts/config --enable CONFIG_DEBUG_VM_RB >>>> ./scripts/config --enable CONFIG_DEBUG_VM_PGFLAGS >>>> ./scripts/config --enable CONFIG_DEBUG_VM_PGTABLE >>>> ./scripts/config --enable CONFIG_PAGE_TABLE_CHECK >>>> >>>> # For mm selftests. >>>> ./scripts/config --enable CONFIG_USERFAULTFD >>>> ./scripts/config --enable CONFIG_TEST_VMALLOC >>>> ./scripts/config --enable CONFIG_GUP_TEST >>>> >>>> Running on VM with 12G memory, split across 2 (emulated) NUMA nodes (needed by >>>> some mm selftests), with kernel command line to reserve hugetlbs and other >>>> features required by some mm selftests: >>>> >>>> " >>>> transparent_hugepage=madvise earlycon root=/dev/vda2 secretmem.enable >>>> hugepagesz=1G hugepages=0:2,1:2 hugepagesz=32M hugepages=0:2,1:2 >>>> default_hugepagesz=2M hugepages=0:64,1:64 hugepagesz=64K hugepages=0:2,1:2 >>>> " >>>> >>>> Ubuntu userspace running off XFS rootfs. Build and run mm selftests from same >>>> git tree. >>>> >>>> >>>> Although I don't think any of this config should make a difference to gup_longterm. >>>> >>>> Looks like your errors are all "ftruncate() failed". I've seen this problem on >>>> our CI system. There it is due to running the tests from NFS file system. What >>>> filesystem are you using? Perhaps you are sharing into the FVP using 9p? That >>>> might also be problematic. >>> >>> That was it. This time I booted up the kernel including your series on >>> QEMU on my M1 and executed the gup_longterm program without the ftruncate >>> failures. When testing your kernel on FVP, I was executing the script from the FVP's host filesystem using 9p. >> >> I'm not sure exactly what the root cause is. Perhaps there isn't enough space on >> the disk? It might be worth enhancing the error log to provide the errno in >> tools/testing/selftests/mm/gup_longterm.c. >> > > Attached is the strace’d gup_longterm executiong log on your > pgtable-boot-speedup-v2 kernel.
Sorry are you saying that it only fails with the pgtable-boot-speedup-v2 patch set applied? I thought we previously concluded that it was independent of that? I was under the impression that it was filesystem related and not something that I was planning to investigate.
> > Thanks, > Itaru. > >> Thanks, >> Ryan >> >>> >>> Thanks, >>> Itaru. >>> >>>> >>>> Does this problem reproduce with v6.9-rc2, without my patches? I except it >>>> probably does? >>>> >>>> Thanks, >>>> Ryan >>>> >>>>> >>>>> Thanks, >>>>> Itaru. > >
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