Messages in this thread | | | Date | Mon, 24 Jan 2022 15:03:48 -0800 | From | Vijay Balakrishna <> | Subject | [arm64] kernel boot slowdown in v5.10.19 -> v5.10.42 update |
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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.
Please let us know if it known/understood or addressed already or being looked into. Any insight is appreciated.
Thanks, Vijay
console output collected with debug prints --
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083] [ 0.000000] Linux version 5.10.42.6-xxx-standard-2008.3.0-local-snapshot-01210432 (oe-user@oe-host) (clang version 10.[ 0.000001] sched_clock: 64 bits at 125MHz, resolution 8ns, wraps every 4398046511100ns [ 0.000003] 2.560781952 MSFT: kernel boot start [ 0.000484] Machine model: xxx [ 0.009379] earlycon: uart8250 at MMIO32 0x0000000068a10000 (options '') [ 0.009383] printk: bootconsole [uart8250] enabled [ 0.009828] before paging_init() [ 0.009977] before map_mem() [ 0.009978] after memblock_mark_nomap() [ 0.152388] after __map_memblock() for loop [ 0.152391] after __map_memblock() kernel_start, kernel_end [ 0.152393] after memblock_clear_nomap [ 0.152394] after map_mem() [ 0.152401] after paging_init() [ 0.153273] NUMA: No NUMA configuration found [ 0.153278] NUMA: Faking a node at [mem 0x0000000080000000-0x000000097fffffff] [ 0.153282] NUMA: NODE_DATA [mem 0x97efec5c0-0x97efedfff] [ 0.153316] Zone ranges: [ 0.153319] Normal [mem 0x0000000080000000-0x000000097fffffff] [ 0.153323] Device empty [ 0.153325] Movable zone start for each node [ 0.153326] Early memory node ranges [ 0.153328] node 0: [mem 0x0000000080000000-0x000000008adfffff] [ 0.153330] node 0: [mem 0x000000008ae00000-0x000000008f223fff] [ 0.153331] node 0: [mem 0x000000008f224000-0x00000000ffffffff] [ 0.153333] node 0: [mem 0x0000000880000000-0x00000008800fffff] [ 0.153334] node 0: [mem 0x0000000880100000-0x000000097fffffff] [ 0.153337] Initmem setup node 0 [mem 0x0000000080000000-0x000000097fffffff] [ 0.153340] On node 0 totalpages: 1572864 [ 0.153342] Normal zone: 24576 pages used for memmap [ 0.153343] Normal zone: 0 pages reserved [ 0.153345] Normal zone: 1572864 pages, LIFO batch:63 [ 0.154507] crashkernel reserved: 0x0000000968e00000 - 0x0000000978e00000 (256 MB)
Console output from PXE boot without "crashkernel=256M" boot parameter -- [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083] [ 0.000000] Linux version 5.10.42.6-xxx-standard-2008.3.0-local-snapshot-01210432 (oe-user@oe-host) (clang version 10.[ 0.000001] sched_clock: 64 bits at 125MHz, resolution 8ns, wraps every 4398046511100ns [ 0.000003] 14.765446920 MSFT: kernel boot start [ 0.000484] Machine model: xxx [ 0.009400] earlycon: uart8250 at MMIO32 0x0000000068a10000 (options '') [ 0.009404] printk: bootconsole [uart8250] enabled [ 0.009835] before paging_init() [ 0.009986] before map_mem() [ 0.009987] after memblock_mark_nomap() [ 0.010154] after __map_memblock() for loop [ 0.010156] after __map_memblock() kernel_start, kernel_end [ 0.010158] after memblock_clear_nomap [ 0.010159] after map_mem() [ 0.010163] after paging_init() [ 0.011002] NUMA: No NUMA configuration found [ 0.011005] NUMA: Faking a node at [mem 0x0000000080000000-0x000000097fffffff] [ 0.011009] NUMA: NODE_DATA [mem 0x97fbc65c0-0x97fbc7fff] [ 0.011037] Zone ranges: [ 0.011038] Normal [mem 0x0000000080000000-0x000000097fffffff] [ 0.011041] Device empty [ 0.011043] Movable zone start for each node [ 0.011044] Early memory node ranges [ 0.011046] node 0: [mem 0x0000000080000000-0x000000008adfffff] [ 0.011048] node 0: [mem 0x000000008ae00000-0x000000008f223fff] [ 0.011049] node 0: [mem 0x000000008f224000-0x00000000ffffffff] [ 0.011050] node 0: [mem 0x0000000880000000-0x00000008800fffff] [ 0.011052] node 0: [mem 0x0000000880100000-0x000000097fffffff] [ 0.011054] Initmem setup node 0 [mem 0x0000000080000000-0x000000097fffffff] [ 0.011056] On node 0 totalpages: 1572864 [ 0.011058] Normal zone: 24576 pages used for memmap [ 0.011060] Normal zone: 0 pages reserved [ 0.011061] Normal zone: 1572864 pages, LIFO batch:63
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