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https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
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5154e60796
Introduce a variable swap_migration_ad_supported to cache whether the arch
supports swap migration A/D bits.
Here one thing to mention is that SWP_MIG_TOTAL_BITS will internally
reference the other macro MAX_PHYSMEM_BITS, which is a function call on
x86 (constant on all the rest of archs).
It's safe to reference it in swapfile_init() because when reaching here
we're already during initcalls level 4 so we must have initialized 5-level
pgtable for x86_64 (right after early_identify_cpu() finishes).
- start_kernel
- setup_arch
- early_cpu_init
- get_cpu_cap --> fetch from CPUID (including X86_FEATURE_LA57)
- early_identify_cpu --> clear X86_FEATURE_LA57 (if early lvl5 not enabled (USE_EARLY_PGTABLE_L5))
- arch_call_rest_init
- rest_init
- kernel_init
- kernel_init_freeable
- do_basic_setup
- do_initcalls --> calls swapfile_init() (initcall level 4)
This should slightly speed up the migration swap entry handlings.
Link: https://lkml.kernel.org/r/20220811161331.37055-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
19 lines
650 B
C
19 lines
650 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SWAPFILE_H
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#define _LINUX_SWAPFILE_H
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/*
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* these were static in swapfile.c but frontswap.c needs them and we don't
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* want to expose them to the dozens of source files that include swap.h
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*/
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extern struct swap_info_struct *swap_info[];
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extern unsigned long generic_max_swapfile_size(void);
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unsigned long arch_max_swapfile_size(void);
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/* Maximum swapfile size supported for the arch (not inclusive). */
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extern unsigned long swapfile_maximum_size;
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/* Whether swap migration entry supports storing A/D bits for the arch */
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extern bool swap_migration_ad_supported;
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#endif /* _LINUX_SWAPFILE_H */
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