Messages in this thread | | | Date | Mon, 27 Feb 2023 06:25:17 +0000 | Subject | Re: [External] Re: [PATCH v12 00/11] Parallel CPU bringup for x86_64 | From | Usama Arif <> |
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On 27/02/2023 06:13, David Woodhouse wrote: > > > On 26 February 2023 20:59:17 GMT, Usama Arif <usama.arif@bytedance.com> wrote: >> >> >> On 26/02/2023 18:31, Oleksandr Natalenko wrote: >>> Hello. >>> >>> On neděle 26. února 2023 12:07:51 CET Usama Arif wrote: >>>> The main code change over v11 is the build error fix by Brian Gerst and >>>> acquiring tr_lock in trampoline_64.S whenever the stack is setup. >>>> >>>> The git history is also rewritten to move the commits that removed >>>> initial_stack, early_gdt_descr and initial_gs earlier in the patchset. >>>> >>>> Thanks, >>>> Usama >>>> >>>> Changes across versions: >>>> v2: Cut it back to just INIT/SIPI/SIPI in parallel for now, nothing more >>>> v3: Clean up x2apic patch, add MTRR optimisation, lock topology update >>>> in preparation for more parallelisation. >>>> v4: Fixes to the real mode parallelisation patch spotted by SeanC, to >>>> avoid scribbling on initial_gs in common_cpu_up(), and to allow all >>>> 24 bits of the physical X2APIC ID to be used. That patch still needs >>>> a Signed-off-by from its original author, who once claimed not to >>>> remember writing it at all. But now we've fixed it, hopefully he'll >>>> admit it now :) >>>> v5: rebase to v6.1 and remeasure performance, disable parallel bringup >>>> for AMD CPUs. >>>> v6: rebase to v6.2-rc6, disabled parallel boot on amd as a cpu bug and >>>> reused timer calibration for secondary CPUs. >>>> v7: [David Woodhouse] iterate over all possible CPUs to find any existing >>>> cluster mask in alloc_clustermask. (patch 1/9) >>>> Keep parallel AMD support enabled in AMD, using APIC ID in CPUID leaf >>>> 0x0B (for x2APIC mode) or CPUID leaf 0x01 where 8 bits are sufficient. >>>> Included sanity checks for APIC id from 0x0B. (patch 6/9) >>>> Removed patch for reusing timer calibration for secondary CPUs. >>>> commit message and code improvements. >>>> v8: Fix CPU0 hotplug by setting up the initial_gs, initial_stack and >>>> early_gdt_descr. >>>> Drop trampoline lock and bail if APIC ID not found in find_cpunr. >>>> Code comments improved and debug prints added. >>>> v9: Drop patch to avoid repeated saves of MTRR at boot time. >>>> rebased and retested at v6.2-rc8. >>>> added kernel doc for no_parallel_bringup and made do_parallel_bringup >>>> __ro_after_init. >>>> v10: Fixed suspend/resume not working with parallel smpboot. >>>> rebased and retested to 6.2. >>>> fixed checkpatch errors. >>>> v11: Added patches from Brian Gerst to remove the global variables initial_gs, >>>> initial_stack, and early_gdt_descr from the 64-bit boot code >>>> (https://lore.kernel.org/all/20230222221301.245890-1-brgerst@gmail.com/). >>>> v12: Fixed compilation errors, acquire tr_lock for every stack setup in >>>> trampoline_64.S. >>>> Rearranged commits for a cleaner git history. >>>> >>>> Brian Gerst (3): >>>> x86/smpboot: Remove initial_stack on 64-bit >>>> x86/smpboot: Remove early_gdt_descr on 64-bit >>>> x86/smpboot: Remove initial_gs >>>> >>>> David Woodhouse (8): >>>> x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel >>>> cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> >>>> cpu/hotplug: Add dynamic parallel bringup states before >>>> CPUHP_BRINGUP_CPU >>>> x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() >>>> x86/smpboot: Split up native_cpu_up into separate phases and document >>>> them >>>> x86/smpboot: Support parallel startup of secondary CPUs >>>> x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel >>>> x86/smpboot: Serialize topology updates for secondary bringup >>>> >>>> .../admin-guide/kernel-parameters.txt | 3 + >>>> arch/x86/include/asm/processor.h | 6 +- >>>> arch/x86/include/asm/realmode.h | 4 +- >>>> arch/x86/include/asm/smp.h | 15 +- >>>> arch/x86/include/asm/topology.h | 2 - >>>> arch/x86/kernel/acpi/sleep.c | 15 +- >>>> arch/x86/kernel/apic/apic.c | 2 +- >>>> arch/x86/kernel/apic/x2apic_cluster.c | 126 ++++--- >>>> arch/x86/kernel/asm-offsets.c | 1 + >>>> arch/x86/kernel/cpu/common.c | 6 +- >>>> arch/x86/kernel/head_64.S | 129 +++++-- >>>> arch/x86/kernel/smpboot.c | 350 +++++++++++++----- >>>> arch/x86/realmode/init.c | 3 + >>>> arch/x86/realmode/rm/trampoline_64.S | 27 +- >>>> arch/x86/xen/smp_pv.c | 4 +- >>>> arch/x86/xen/xen-head.S | 2 +- >>>> include/linux/cpuhotplug.h | 2 + >>>> include/linux/smpboot.h | 7 + >>>> kernel/cpu.c | 31 +- >>>> kernel/smpboot.h | 2 - >>>> 20 files changed, 537 insertions(+), 200 deletions(-) >>> >>> With `CONFIG_FORCE_NR_CPUS=y` this results in: >>> >>> ``` >>> ld: vmlinux.o: in function `secondary_startup_64_no_verify': >>> (.head.text+0x10c): undefined reference to `nr_cpu_ids' >>> ``` >>> >>> That's because in `arch/x86/kernel/head_64.S` `secondary_startup_64_no_verify()` refers to `nr_cpu_ids` under `#ifdef CONFIG_SMP`, but this symbol is available under the following conditions: >>> >>> ``` >>> 38 #if (NR_CPUS == 1) || defined(CONFIG_FORCE_NR_CPUS) >>> 39 #define nr_cpu_ids ((unsigned int)NR_CPUS) >>> 40 #else >>> 41 extern unsigned int nr_cpu_ids; >>> 42 #endif >>> >>> 1090 #if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS) >>> 1091 /* Setup number of possible processor ids */ >>> 1092 unsigned int nr_cpu_ids __read_mostly = NR_CPUS; >>> 1093 EXPORT_SYMBOL(nr_cpu_ids); >>> 1094 #endif >>> ``` >>> >>> So having `CONFIG_SMP=y` and, for instance, `CONFIG_NR_CPUS=320`, it is possible to compile out `EXPORT_SYMBOL(nr_cpu_ids);` if `CONFIG_FORCE_NR_CPUS=y` is set. >>> >> >> I think something like below diff should work in all scenarios? > > I'd've changed the asm side to use the constant limit.
Yup, just needed the morning coffee :) Had sent the proper fix in https://lore.kernel.org/all/5e8ad90a-1dc6-95c2-e020-5e95da6f9eda@bytedance.com/#t
I guess the diff is still small over v12 (including the cosmetic changes) to send out a new version so soon, probably better to wait a couple of days incase something else comes up as well?
Thanks, Usama
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