Messages in this thread | | | Date | Fri, 28 Jan 2022 10:03:09 -0800 | Subject | Re: [arm64] kernel boot slowdown in v5.10.19 -> v5.10.42 update | From | Vijay Balakrishna <> |
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On 1/28/2022 4:06 AM, Catalin Marinas wrote: > On Mon, Jan 24, 2022 at 03:03:48PM -0800, Vijay Balakrishna wrote: >> We noticed 150ms kernel boot slowdown back in June, 2021, when moving from >> v5.10.19 to v5.10.42. This on a 8GB SoC. Only recently we investigated >> this issue and found the regression is introduced by a change in map_mem() >> (paging_init() -> map_mem() -> __map_memblock(), in particular "map all the >> memory banks" for loop) by patch >> >> 2687275a5843d1089687f08fc64eb3f3b026a169 >> arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required >> >> above is a follow up to >> >> 0a30c53573b07d5561457e41fb0ab046cd857da5 >> arm64: mm: Move reserve_crashkernel() into mem_init()) >> >> which deferred crashkernel reservation into mem_init(). >> >> The ~150ms slowdown disappears on booting without "crashkernel=.." on kernel >> command-line. > > Is CONFIG_RODATA_FULL_DEFAULT_ENABLED set in your config file? It may > cause the same slowdown. I suspect it's because we end up mapping the > RAM at the page granularity so more loops and slightly higher TLB > pressure. Not sure we can do much about >
Catalin,
Thanks for your reply.
CONFIG_RODATA_FULL_DEFAULT_ENABLED is not set in our config for boot time performance reasons.
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