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charset="UTF-8" X-Stat-Signature: e7tkbmk99ipdtbsn5yr6rj4qzg9sth4o X-Rspamd-Queue-Id: 6FC60C0002 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1790414694-34258 X-HE-Meta: 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 6UOf7Hh0 1aP9fB0yzmGhVkeCS//3ma+N6EvhbfiZCTSG26yBaACV09JzzDJ/mKKGQg5SF7npM73WIueyp8aPxwAeOw8CusUx0RsOPtm0IU7i/nqoYjssDs8+xJTa2pp25to2H9tUZR3FiVoaX+lpNPr8HhqJILkRpinGWTT3JzrTVeaHLnQehk3VPTy6TLgg8ydrpEHuGsABPeoIqc3zDxjjT3PnzZIopbEnuKmjym3TMQZxrYxD09/ZHIBSw5sqEFhi1KUVwSgVf7I5p1RWa0BLxCyBCXynHmbVxlI2zWEu9REttXv/Nu8lxPF6s4Us223zannclpKBRncXrc4mfTH/dR9a9rfh/LkiFTfY9HJo2DJMuonwX2VvqOGm7quHX2JjHF+2lqLadjO26sSMacGScEY0nbeep0jAI4rC2ODahWFfUXEIj5nCMJcmrgnLiqDxBBih03PFPwu+8Mm/39JMpni50IBw02lhc+G9XAblcj+ca/MzThdnAzOS+NzGXddDqP6geBEGgiq6r/H1eyTrk8YZIhbKv71+/uEA1rfLdocIjlEUdlRMWoHdsA/n3giqNeQbcyZH+d1Y23cH4BJNAjqtjAR4de50pz1S3EVEG Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Use binary search (memblock_bsearch_start) in memblock_add_range() and memblock_isolate_range() to locate candidate regions instead of linearly scanning from index 0. Under heavy memory fragmentation (such as KHO page preservation registering hundreds of thousands of disjoint folios), scanning from index 0 on every insertion and isolation results in O(N^2) complexity, causing boot-time memory retrieval to take several minutes (~268s for 393k pages). Using binary search reduces the worst-case complexity to O(N log N) (and O(N) for sequential appends), cutting KHO memory retrieval time from ~268s to ~50ms. memblock_search() open codes the same binary search, so reimplement it on top of the new helper. Signed-off-by: Tarun Sahu mm/memblock.c | 53 +++++++++++++++++++++++++++++++++++---------------- 1 file changed, 37 insertions(+), 16 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index 59dda7d085f3..87c71435c80c 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -586,6 +586,33 @@ static void __init_memblock memblock_insert_region(struct memblock_type *type, type->total_size += size; } +/** + * memblock_bsearch_start - Find the first region index where rend > base + * @type: memblock type to search + * @base: base physical address of the candidate range + * + * Returns the first region index that could potentially overlap @base. + */ +static int __init_memblock memblock_bsearch_start(struct memblock_type *type, + phys_addr_t base) +{ + int mid, low = 0; + int high = type->cnt; + + if (type->cnt && base >= type->regions[type->cnt - 1].base + + type->regions[type->cnt - 1].size) + return type->cnt; + + while (low < high) { + mid = (low + high) / 2; + if (type->regions[mid].base + type->regions[mid].size <= base) + low = mid + 1; + else + high = mid; + } + return low; +} + /** * memblock_add_range - add new memblock region * @type: memblock type to add new region into @@ -609,7 +636,7 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, bool insert = false; phys_addr_t obase = base; phys_addr_t end = base + memblock_cap_size(base, &size); - int idx, nr_new, start_rgn = -1, end_rgn; + int idx, start_idx, nr_new, start_rgn = -1, end_rgn; if (!size) return 0; @@ -644,8 +671,9 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, */ base = obase; nr_new = 0; + start_idx = memblock_bsearch_start(type, base); - for (idx = 0; idx < type->cnt; idx++) { + for (idx = start_idx; idx < type->cnt; idx++) { struct memblock_region *rgn = &type->regions[idx]; phys_addr_t rbase = rgn->base; phys_addr_t rend = rbase + rgn->size; @@ -809,7 +837,7 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type, int *start_rgn, int *end_rgn) { phys_addr_t end = base + memblock_cap_size(base, &size); - int idx; + int idx, start_idx; *start_rgn = *end_rgn = 0; @@ -821,7 +849,9 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type, if (memblock_double_array(type, base, size) < 0) return -ENOMEM; - for (idx = 0; idx < type->cnt; idx++) { + start_idx = memblock_bsearch_start(type, base); + + for (idx = start_idx; idx < type->cnt; idx++) { struct memblock_region *rgn = &type->regions[idx]; phys_addr_t rbase = rgn->base; phys_addr_t rend = rbase + rgn->size; @@ -2062,19 +2092,10 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit) static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr) { - unsigned int left = 0, right = type->cnt; + int idx = memblock_bsearch_start(type, addr); - do { - unsigned int mid = (right + left) / 2; - - if (addr < type->regions[mid].base) - right = mid; - else if (addr >= (type->regions[mid].base + - type->regions[mid].size)) - left = mid + 1; - else - return mid; - } while (left < right); + if (idx < type->cnt && addr >= type->regions[idx].base) + return idx; return -1; } base-commit: 1f18d740165163910df64d3063e1ad31648bc5e0 -- 2.56.0.rc1.315.gc6ed9934b7-goog