diff options
| author | Evan Green <[email protected]> | 2023-11-06 14:58:55 -0800 |
|---|---|---|
| committer | Palmer Dabbelt <[email protected]> | 2023-11-07 15:13:47 -0800 |
| commit | 55e0bf49a0d0387d682d696e41cada071f516075 (patch) | |
| tree | 49f98f093525d2bcd9ee6d1bca401cbbf7db60d1 /arch/riscv/kernel/smpboot.c | |
| parent | 6eb7a6445b76a2fced91ebcf93d7a9073258c8cf (diff) | |
RISC-V: Probe misaligned access speed in parallel
Probing for misaligned access speed takes about 0.06 seconds. On a
system with 64 cores, doing this in smp_callin() means it's done
serially, extending boot time by 3.8 seconds. That's a lot of boot time.
Instead of measuring each CPU serially, let's do the measurements on
all CPUs in parallel. If we disable preemption on all CPUs, the
jiffies stop ticking, so we can do this in stages of 1) everybody
except core 0, then 2) core 0. The allocations are all done outside of
on_each_cpu() to avoid calling alloc_pages() with interrupts disabled.
For hotplugged CPUs that come in after the boot time measurement,
register CPU hotplug callbacks, and do the measurement there. Interrupts
are enabled in those callbacks, so they're fine to do alloc_pages() in.
Reported-by: Jisheng Zhang <[email protected]>
Closes: https://lore.kernel.org/all/mhng-9359993d-6872-4134-83ce-c97debe1cf9a@palmer-ri-x1c9/T/#mae9b8f40016f9df428829d33360144dc5026bcbf
Fixes: 584ea6564bca ("RISC-V: Probe for unaligned access speed")
Signed-off-by: Evan Green <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>
Diffstat (limited to 'arch/riscv/kernel/smpboot.c')
| -rw-r--r-- | arch/riscv/kernel/smpboot.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c index d69c628c24f4..d162bf339beb 100644 --- a/arch/riscv/kernel/smpboot.c +++ b/arch/riscv/kernel/smpboot.c @@ -247,7 +247,6 @@ asmlinkage __visible void smp_callin(void) riscv_ipi_enable(); numa_add_cpu(curr_cpuid); - check_unaligned_access(curr_cpuid); set_cpu_online(curr_cpuid, 1); if (has_vector()) { |