Re: [PATCH v3 00/35] SLUB: reduce irq disabled scope and make it RT compatible

From: Sebastian Andrzej Siewior
Date: Thu Jul 29 2021 - 11:26:14 EST


On 2021-07-29 15:20:57 [+0200], Vlastimil Babka wrote:
> Changes since v2 [5]:

With PARTIAL enabled on top of -rc3:

| root@debpg:~# grep ^kmalloc-512 /proc/slabinfo
| kmalloc-512 3552 3552 512 32 4 : tunables 0 0 0 : slabdata 111 111 0
| root@debpg:~# hackbench -g80
| Running in process mode with 80 groups using 40 file descriptors each (== 3200 tasks)
| Each sender will pass 100 messages of 100 bytes
| Time: 0.643
| root@debpg:~# grep ^kmalloc-512 /proc/slabinfo
| kmalloc-512 954080 954080 512 32 4 : tunables 0 0 0 : slabdata 29815 29815 0
| root@debpg:~# hackbench -g80
| Running in process mode with 80 groups using 40 file descriptors each (== 3200 tasks)
| Each sender will pass 100 messages of 100 bytes
| Time: 0.604
| root@debpg:~# grep ^kmalloc-512 /proc/slabinfo
| kmalloc-512 1647904 1647904 512 32 4 : tunables 0 0 0 : slabdata 51497 51497 0
| root@debpg:~# echo 1 > /sys/kernel/slab/kmalloc-512/shrink
| root@debpg:~# grep ^kmalloc-512 /proc/slabinfo
| kmalloc-512 640 1120 512 32 4 : tunables 0 0 0 : slabdata 35 35 0

otherwise a few more hackbench invocations without manual shirnk lead to
OOM-killer:
| oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,task=systemd-logind,pid=1713,uid=0
| Out of memory: Killed process 1713 (systemd-logind) total-vm:15720kB, anon-rss:956kB, file-rss:0kB, shmem-rss:0kB, UID:0 pgtables:72kB oom_score_adj:0
| Mem-Info:
| active_anon:56 inactive_anon:24782 isolated_anon:0
| active_file:13 inactive_file:45 isolated_file:0
| unevictable:0 dirty:0 writeback:0
| slab_reclaimable:8749 slab_unreclaimable:894017
| mapped:68 shmem:118 pagetables:28612 bounce:0
| free:8407 free_pcp:36 free_cma:0
| Node 0 active_anon:224kB inactive_anon:99128kB active_file:260kB inactive_file:712kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:764kB dirty:0kB writebaco
| Node 0 DMA free:15360kB min:28kB low:40kB high:52kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writependiB
| lowmem_reserve[]: 0 1939 3915 3915
| Node 0 DMA32 free:11696kB min:3960kB low:5944kB high:7928kB reserved_highatomic:0KB active_anon:0kB inactive_anon:40740kB active_file:0kB inactive_file:4kB unevictable:0kB
| lowmem_reserve[]: 0 0 1975 1975
| Node 0 Normal free:5692kB min:4032kB low:6052kB high:8072kB reserved_highatomic:0KB active_anon:224kB inactive_anon:58440kB active_file:440kB inactive_file:100kB unevictaB
| lowmem_reserve[]: 0 0 0 0
| Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15360kB
| Node 0 DMA32: 11*4kB (UM) 15*8kB (M) 20*16kB (UME) 12*32kB (UME) 7*64kB (ME) 5*128kB (UME) 4*256kB (UM) 6*512kB (ME) 4*1024kB (M) 1*2048kB (M) 0*4096kB = 12196kB
| Node 0 Normal: 324*4kB (UME) 221*8kB (UME) 60*16kB (UM) 24*32kB (UME) 5*64kB (UM) 2*128kB (U) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 5368kB
| Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
| 189 total pagecache pages
| 0 pages in swap cache
| Swap cache stats: add 0, delete 0, find 0/0
| Free swap = 0kB
| Total swap = 0kB
| 1048432 pages RAM
| 0 pages HighMem/MovableOnly
| 41108 pages reserved
| Unreclaimable slab info:

| kmalloc-512 2144352KB 2144352KB

This does not happen if I disable SLUB_CPU_PARTIAL.

Sebastian