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Subject: Re: [PATCH v3 00/35] SLUB: reduce irq disabled scope and make it RT
 compatible
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Mike Galbraith <efault@gmx.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mel Gorman <mgorman@techsingularity.net>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Jann Horn <jannh@google.com>
References: <20210729132132.19691-1-vbabka@suse.cz>
 <20210729152400.ed35ocv5jtpf3ns5@linutronix.de>
From:   Vlastimil Babka <vbabka@suse.cz>
Message-ID: <803269ba-d4f4-6016-067f-8f9e02b3c794@suse.cz>
Date:   Thu, 29 Jul 2021 17:27:18 +0200
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On 7/29/21 5:24 PM, Sebastian Andrzej Siewior wrote:
> On 2021-07-29 15:20:57 [+0200], Vlastimil Babka wrote:
>> Changes since v2 [5]:
> 
> With PARTIAL enabled on top of -rc3:

Is that also PREEMPT_RT? Interesting...

> | 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
>