Am 05.09.19 um 13:40 schrieb Michal Hocko: > On Thu 05-09-19 13:27:10, Stefan Priebe - Profihost AG wrote: >> Hello all, >> >> i hope you can help me again to understand the current MemAvailable >> value in the linux kernel. I'm running a 4.19.52 kernel + psi patches in >> this case. >> >> I'm seeing the following behaviour i don't understand and ask for help. >> >> While MemAvailable shows 5G the kernel starts to drop cache from 4G down >> to 1G while the apache spawns some PHP processes. After that the PSI >> mem.some value rises and the kernel tries to reclaim memory but >> MemAvailable stays at 5G. >> >> Any ideas? > > Can you collect /proc/vmstat (every second or so) and post it while this > is the case please? Yes sure. But i don't know which event you mean exactly. Current situation is PSI / memory pressure is > 20 but: This is the current status where MemAvailable show 5G but Cached is already dropped to 1G coming from 4G: meminfo: MemTotal: 16423116 kB MemFree: 5280736 kB MemAvailable: 5332752 kB Buffers: 2572 kB Cached: 1225112 kB SwapCached: 0 kB Active: 8934976 kB Inactive: 1026900 kB Active(anon): 8740396 kB Inactive(anon): 873448 kB Active(file): 194580 kB Inactive(file): 153452 kB Unevictable: 19900 kB Mlocked: 19900 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 1980 kB Writeback: 0 kB AnonPages: 8423480 kB Mapped: 978212 kB Shmem: 875680 kB Slab: 839868 kB SReclaimable: 383396 kB SUnreclaim: 456472 kB KernelStack: 22576 kB PageTables: 49824 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 8211556 kB Committed_AS: 32060624 kB VmallocTotal: 34359738367 kB VmallocUsed: 0 kB VmallocChunk: 0 kB Percpu: 118048 kB HardwareCorrupted: 0 kB AnonHugePages: 6406144 kB ShmemHugePages: 0 kB ShmemPmdMapped: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 0 kB DirectMap4k: 2580336 kB DirectMap2M: 14196736 kB DirectMap1G: 2097152 kB vmstat shows: nr_free_pages 1320053 nr_zone_inactive_anon 218362 nr_zone_active_anon 2185108 nr_zone_inactive_file 38363 nr_zone_active_file 48645 nr_zone_unevictable 4975 nr_zone_write_pending 495 nr_mlock 4975 nr_page_table_pages 12553 nr_kernel_stack 22576 nr_bounce 0 nr_zspages 0 nr_free_cma 0 numa_hit 13916119899 numa_miss 0 numa_foreign 0 numa_interleave 15629 numa_local 13916119899 numa_other 0 nr_inactive_anon 218362 nr_active_anon 2185164 nr_inactive_file 38363 nr_active_file 48645 nr_unevictable 4975 nr_slab_reclaimable 95849 nr_slab_unreclaimable 114118 nr_isolated_anon 0 nr_isolated_file 0 workingset_refault 71365357 workingset_activate 20281670 workingset_restore 8995665 workingset_nodereclaim 326085 nr_anon_pages 2105903 nr_mapped 244553 nr_file_pages 306921 nr_dirty 495 nr_writeback 0 nr_writeback_temp 0 nr_shmem 218920 nr_shmem_hugepages 0 nr_shmem_pmdmapped 0 nr_anon_transparent_hugepages 3128 nr_unstable 0 nr_vmscan_write 0 nr_vmscan_immediate_reclaim 1833104 nr_dirtied 386544087 nr_written 259220036 nr_dirty_threshold 265636 nr_dirty_background_threshold 132656 pgpgin 1817628997 pgpgout 3730818029 pswpin 0 pswpout 0 pgalloc_dma 0 pgalloc_dma32 5790777997 pgalloc_normal 20003662520 pgalloc_movable 0 allocstall_dma 0 allocstall_dma32 0 allocstall_normal 39 allocstall_movable 1980089 pgskip_dma 0 pgskip_dma32 0 pgskip_normal 0 pgskip_movable 0 pgfree 26637215947 pgactivate 316722654 pgdeactivate 261039211 pglazyfree 0 pgfault 17719356599 pgmajfault 30985544 pglazyfreed 0 pgrefill 286826568 pgsteal_kswapd 36740923 pgsteal_direct 349291470 pgscan_kswapd 36878966 pgscan_direct 395327492 pgscan_direct_throttle 0 zone_reclaim_failed 0 pginodesteal 49817087 slabs_scanned 597956834 kswapd_inodesteal 1412447 kswapd_low_wmark_hit_quickly 39 kswapd_high_wmark_hit_quickly 319 pageoutrun 3585 pgrotated 2873743 drop_pagecache 0 drop_slab 0 oom_kill 0 pgmigrate_success 839062285 pgmigrate_fail 507313 compact_migrate_scanned 9619077010 compact_free_scanned 67985619651 compact_isolated 1684537704 compact_stall 205761 compact_fail 182420 compact_success 23341 compact_daemon_wake 2 compact_daemon_migrate_scanned 811 compact_daemon_free_scanned 490241 htlb_buddy_alloc_success 0 htlb_buddy_alloc_fail 0 unevictable_pgs_culled 1006521 unevictable_pgs_scanned 0 unevictable_pgs_rescued 997077 unevictable_pgs_mlocked 1319203 unevictable_pgs_munlocked 842471 unevictable_pgs_cleared 470531 unevictable_pgs_stranded 459613 thp_fault_alloc 20263113 thp_fault_fallback 3368635 thp_collapse_alloc 226476 thp_collapse_alloc_failed 17594 thp_file_alloc 0 thp_file_mapped 0 thp_split_page 1159 thp_split_page_failed 3927 thp_deferred_split_page 20348941 thp_split_pmd 53361 thp_split_pud 0 thp_zero_page_alloc 1 thp_zero_page_alloc_failed 0 thp_swpout 0 thp_swpout_fallback 0 balloon_inflate 0 balloon_deflate 0 balloon_migrate 0 swap_ra 0 swap_ra_hit 0 Greets, Stefan
