Re: Fwd: MDS memory usage is very high

Daniel Carrasco <d.carrasco@xxxxxxxxx> · Mon, 23 Jul 2018 21:18:24 +0200

Hi,
I forgot to say that maybe the Diff is lower than real (8Mb), because the memory usage was still high and i've prepared a new configuration with lower limit (5Mb). I've not reloaded the daemons for now, but maybe the configuration was loaded again today and that's the reason why is using less than 1Gb of RAM just now. Of course I've not rebooted the machine, but maybe if the daemon was killed for high memory usage then the new configuration is loaded now.

Greetings!

2018-07-19 11:35 GMT+02:00 Daniel Carrasco <d.carrasco@xxxxxxxxx>:
Hello again,
It is still early to say that is working fine now, but looks like the MDS memory is now under 20% of RAM and the most of time between 6-9%. Maybe was a mistake on configuration.

As appointment, I've changed this client config:
[global]
...
bluestore_cache_size_ssd = 805306360
bluestore_cache_size_hdd = 805306360
mds_cache_memory_limit = 536870910

[client]
  client_reconnect_stale = true
  client_cache_size = 32768
  client_mount_timeout = 30
  client_oc_max_objects = 2000
  client_oc_size = 629145600
  rbd_cache = true
  rbd_cache_size = 671088640

for this (just client cache sizes / 10):
[global]
...
bluestore_cache_size_ssd = 80530636
bluestore_cache_size_hdd = 80530636
mds_cache_memory_limit = 53687091

[client]
  client_cache_size = 32768
  client_mount_timeout = 30
  client_oc_max_objects = 2000
  client_oc_size = 62914560
  rbd_cache = true
  rbd_cache_size = 67108864

Now the heap stats are:
mds.kavehome-mgto-pro-fs01 tcmalloc heap stats:------------------------------------------------MALLOC:      714063568 (  681.0 MiB) Bytes in use by application
MALLOC: +            0 (    0.0 MiB) Bytes in page heap freelistMALLOC: +    132992224 (  126.8 MiB) Bytes in central cache freelist
MALLOC: +     21929920 (   20.9 MiB) Bytes in transfer cache freelist
MALLOC: +     31806608 (   30.3 MiB) Bytes in thread cache freelists
MALLOC: +     30666912 (   29.2 MiB) Bytes in malloc metadata
MALLOC:   ------------
MALLOC: =    931459232 (  888.3 MiB) Actual memory used (physical + swap)
MALLOC: +  21886803968 (20872.9 MiB) Bytes released to OS (aka unmapped)
MALLOC:   ------------
MALLOC: =  22818263200 (21761.2 MiB) Virtual address space used
MALLOC:
MALLOC:          21311              Spans in use
MALLOC:             18              Thread heaps in use
MALLOC:           8192              Tcmalloc page size
------------------------------------------------
Call ReleaseFreeMemory() to release freelist memory to the OS (via madvise()).
Bytes released to the OS take up virtual address space but no physical memory.

And sometimes even better (taken later than above):
mds.kavehome-mgto-pro-fs01 tcmalloc heap stats:------------------------------------------------MALLOC:      516434072 (  492.5 MiB) Bytes in use by application
MALLOC: +            0 (    0.0 MiB) Bytes in page heap freelistMALLOC: +      7564936 (    7.2 MiB) Bytes in central cache freelist
MALLOC: +      2751072 (    2.6 MiB) Bytes in transfer cache freelist
MALLOC: +      2707072 (    2.6 MiB) Bytes in thread cache freelists
MALLOC: +      2715808 (    2.6 MiB) Bytes in malloc metadata
MALLOC:   ------------
MALLOC: =    532172960 (  507.5 MiB) Actual memory used (physical + swap)
MALLOC: +       573440 (    0.5 MiB) Bytes released to OS (aka unmapped)
MALLOC:   ------------
MALLOC: =    532746400 (  508.1 MiB) Virtual address space used
MALLOC:
MALLOC:          21990              Spans in use
MALLOC:             16              Thread heaps in use
MALLOC:           8192              Tcmalloc page size
------------------------------------------------
Call ReleaseFreeMemory() to release freelist memory to the OS (via madvise()).
Bytes released to the OS take up virtual address space but no physical memory.

Greetings!!

2018-07-19 10:24 GMT+02:00 Daniel Carrasco <d.carrasco@xxxxxxxxx>:
Hello,

Finally I've to remove CephFS and use a simple NFS, because the MDS daemon starts to use a lot of memory and is unstable. After reboot one node because it started to swap (the cluster will be able to survive without a node), the cluster goes down because one of the other MDS starts to use about 15Gb of RAM and crash all the time, so the cluster is unable to come back. The only solution is to reboot all nodes and is not good for HA.
If somebody knows something about this, I'll be pleased to test it on a test environment to see if we can find a solution.

Greetings!

2018-07-19 1:07 GMT+02:00 Daniel Carrasco <d.carrasco@xxxxxxxxx>:
Thanks again,
I was trying to use fuse client instead Ubuntu 16.04 kernel module to see if maybe is a client side problem, but CPU usage on fuse client is very high (a 100% and even more in a two cores machine), so I'd to rever to kernel client that uses much less CPU.
Is a web server, so maybe the problem is that. PHP and Nginx should open a lot of files and maybe that uses a lot of RAM.

For now I've rebooted the machine because is the only way to free the memory, but I cannot restart the machine every few hours...

Greetings!!

2018-07-19 1:00 GMT+02:00 Gregory Farnum <gfarnum@xxxxxxxxxx>:
Wow, yep, apparently the MDS has another 9GB of allocated RAM outside of the cache! Hopefully one of the current FS users or devs has some idea. All I can suggest is looking to see if there are a bunch of stuck requests or something that are taking up memory which isn’t properly counted.
On Wed, Jul 18, 2018 at 3:48 PM Daniel Carrasco <d.carrasco@xxxxxxxxx> wrote:
Hello, thanks for your response.

This is what I get:
# ceph tell mds.kavehome-mgto-pro-fs01  heap stats
2018-07-19 00:43:46.142560 7f5a7a7fc700  0 client.1318388 ms_handle_reset on 10.22.0.168:6800/1129848128
2018-07-19 00:43:46.181133 7f5a7b7fe700  0 client.1318391 ms_handle_reset on 10.22.0.168:6800/1129848128
mds.kavehome-mgto-pro-fs01 tcmalloc heap stats:------------------------------------------------
MALLOC:     9982980144 ( 9520.5 MiB) Bytes in use by application
MALLOC: +            0 (    0.0 MiB) Bytes in page heap freelist
MALLOC: +    172148208 (  164.2 MiB) Bytes in central cache freelist
MALLOC: +     19031168 (   18.1 MiB) Bytes in transfer cache freelist
MALLOC: +     23987552 (   22.9 MiB) Bytes in thread cache freelists
MALLOC: +     20869280 (   19.9 MiB) Bytes in malloc metadata
MALLOC:   ------------
MALLOC: =  10219016352 ( 9745.6 MiB) Actual memory used (physical + swap)
MALLOC: +   3913687040 ( 3732.4 MiB) Bytes released to OS (aka unmapped)
MALLOC:   ------------
MALLOC: =  14132703392 (13478.0 MiB) Virtual address space used
MALLOC:
MALLOC:          63875              Spans in use
MALLOC:             16              Thread heaps in use
MALLOC:           8192              Tcmalloc page size
------------------------------------------------
Call ReleaseFreeMemory() to release freelist memory to the OS (via madvise()).
Bytes released to the OS take up virtual address space but no physical memory.

I've tried the release command but it keeps using the same memory.

greetings!

2018-07-19 0:25 GMT+02:00 Gregory Farnum <gfarnum@xxxxxxxxxx>:
The MDS think it's using 486MB of cache right now, and while that's

not a complete accounting (I believe you should generally multiply by

1.5 the configured cache limit to get a realistic memory consumption

model) it's obviously a long way from 12.5GB. You might try going in

with the "ceph daemon" command and looking at the heap stats (I forget

the exact command, but it will tell you if you run "help" against it)

and seeing what those say — you may have one of the slightly-broken

base systems and find that running the "heap release" (or similar

wording) command will free up a lot of RAM back to the OS!

-Greg

On Wed, Jul 18, 2018 at 1:53 PM, Daniel Carrasco <d.carrasco@xxxxxxxxx> wrote:

> Hello,

>

> I've created a 3 nodes cluster with MON, MGR, OSD and MDS on all (2 MDS

> actives), and I've noticed that MDS is using a lot of memory (just now is

> using 12.5GB of RAM):

> # ceph daemon mds.kavehome-mgto-pro-fs01 dump_mempools | jq -c '.mds_co';

> ceph daemon mds.kavehome-mgto-pro-fs01 perf dump | jq '.mds_mem.rss'

> {"items":9272259,"bytes":510032260}

> 12466648

>

> I've configured the limit:

> mds_cache_memory_limit = 536870912

>

> But looks like is ignored, because is about 512Mb and is using a lot more.

>

> Is there any way to limit the memory usage of MDS, because is giving a lot

> of troubles because start to swap.

> Maybe I've to limit the cached inodes?

>

> The other active MDS is using a lot less memory (2.5Gb). but also is using

> more than 512Mb. The standby MDS is not using memory it all.

>

> I'm using the version:

> ceph version 12.2.7 (3ec878d1e53e1aeb47a9f619c49d9e7c0aa384d5) luminous

> (stable).

>

> Thanks!!

> --

> _________________________________________

>

>       Daniel Carrasco Marín

>       Ingeniería para la Innovación i2TIC, S.L.

>       Tlf:  +34 911 12 32 84 Ext: 223

>       www.i2tic.com

> _________________________________________

>

>

>

> --

> _________________________________________

>

>       Daniel Carrasco Marín

>       Ingeniería para la Innovación i2TIC, S.L.

>       Tlf:  +34 911 12 32 84 Ext: 223

>       www.i2tic.com

> _________________________________________

>

> _______________________________________________

> ceph-users mailing list

> ceph-users@xxxxxxxxxxxxxx

> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com

>

-- 
_________________________________________

      Daniel Carrasco Marín
      Ingeniería para la Innovación i2TIC, S.L.
      Tlf:  +34 911 12 32 84 Ext: 223
      www.i2tic.com
_________________________________________

-- 
_________________________________________

      Daniel Carrasco Marín
      Ingeniería para la Innovación i2TIC, S.L.
      Tlf:  +34 911 12 32 84 Ext: 223
      www.i2tic.com
_________________________________________

-- 
_________________________________________

      Daniel Carrasco Marín
      Ingeniería para la Innovación i2TIC, S.L.
      Tlf:  +34 911 12 32 84 Ext: 223
      www.i2tic.com
_________________________________________

-- 
_________________________________________

      Daniel Carrasco Marín
      Ingeniería para la Innovación i2TIC, S.L.
      Tlf:  +34 911 12 32 84 Ext: 223
      www.i2tic.com
_________________________________________

-- 
_________________________________________

      Daniel Carrasco Marín
      Ingeniería para la Innovación i2TIC, S.L.
      Tlf:  +34 911 12 32 84 Ext: 223
      www.i2tic.com
_________________________________________

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