Function report

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:mm\page_alloc.c Create Date:2022-07-28 15:08:08
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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Name:setup_per_zone_lowmem_reserve - called whenever* sysctl_lowmem_reserve_ratio changes. Ensures that each zone* has a correct pages reserved value, so an adequate number of* pages are left in the zone after a successful __alloc_pages().

Proto:static void setup_per_zone_lowmem_reserve(void)

Type:void

Parameter:Nothing

7694  When j < MAX_NR_ZONES cycle
7695  zone = node_zones + j
7696  managed_pages = zone_managed_pages(zone)
7698  * We don't know if the memory that we're going to allocate will be * freeable or/and it will be released eventually, so to avoid totally * wasting several GB of ram we must reserve some of the lower zone * memory (otherwise we risk to run OOM on the lower [j] = 0
7700  idx = j
7701  When idx cycle
7704  idx--
7705  lower_zone = node_zones + idx
7707  If sults with 256, 32 in the lowmem_reserve sysctl:* 1G machine -> (16M dma, 800M-16M normal, 1G-800M high)* 1G machine -> (16M dma, 784M normal, 224M high)* NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA* HIGHMEM allocation will leave [idx] < 1 Then
7710  Else
7714  managed_pages += zone_managed_pages(lower_zone)
7720  alculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio* or min_free_kbytes changes.
Caller
NameDescribe
init_per_zone_wmark_minInitialise min_free_kbytes
lowmem_reserve_ratio_sysctl_handlerlowmem_reserve_ratio_sysctl_handler - just a wrapper around* proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()* whenever sysctl_lowmem_reserve_ratio changes.* The reserve ratio obviously has absolutely no relation with the