Coincidentally Adam on our core team just reported this morning that he
saw extremely high bluestore_cache_other memory usage while running
compression performance tests as well. That may indicate we have a
memory leak related to the compression code. I doubt setting the
memory_target to 3GiB will help in the long run as that will just
attempt to compensate by decreasing the other caches until nothing else
can be shrunk. Adam said he's planning to investigate so hopefully we
will know more soon.
Mark
On 5/13/20 10:52 AM, Rafał Wądołowski wrote:
Mark,
Unfortunetly I closed terminal with mempool. But there was a lot of
bytes used by bluestore_cache_other. That was the highest value (about
85%). The onode cache takes about 10%. PGlog and osdmaps was okey, low
values. I saw some ideas that maybe compression_mode force in pool can
make a mess.
One more thing, we are running stupid allocator. Right now I am
decrease the osd_memory_target to 3GiB and will wait if ram problem
occurs.
Regards,
*/Rafał Wądołowski/*
------------------------------------------------------------------------
*From:* Mark Nelson <mnelson@xxxxxxxxxx>
*Sent:* Wednesday, May 13, 2020 3:30 PM
*To:* ceph-users@xxxxxxx <ceph-users@xxxxxxx>
*Subject:* Re: Memory usage of OSD
On 5/13/20 12:43 AM, Rafał Wądołowski wrote:
> Hi,
> I noticed strange situation in one of our clusters. The OSD deamons
are taking too much RAM.
> We are running 12.2.12 and have default configuration of
osd_memory_target (4GiB).
> Heap dump shows:
>
> osd.2969 dumping heap profile now.
> ------------------------------------------------
> MALLOC: 6381526944 ( 6085.9 MiB) Bytes in use by application
> MALLOC: + 0 ( 0.0 MiB) Bytes in page heap freelist
> MALLOC: + 173373288 ( 165.3 MiB) Bytes in central cache freelist
> MALLOC: + 17163520 ( 16.4 MiB) Bytes in transfer cache freelist
> MALLOC: + 95339512 ( 90.9 MiB) Bytes in thread cache freelists
> MALLOC: + 28995744 ( 27.7 MiB) Bytes in malloc metadata
> MALLOC: ------------
> MALLOC: = 6696399008 ( 6386.2 MiB) Actual memory used (physical +
swap)
> MALLOC: + 218267648 ( 208.2 MiB) Bytes released to OS (aka unmapped)
> MALLOC: ------------
> MALLOC: = 6914666656 ( 6594.3 MiB) Virtual address space used
> MALLOC:
> MALLOC: 408276 Spans in use
> MALLOC: 75 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.
>
> IMO "Bytes in use by application" should be less than
osd_memory_target. Am I correct?
> I checked heap dump with google-pprof and got following results.
> Total: 149.4 MB
> 60.5 40.5% 40.5% 60.5 40.5%
rocksdb::UncompressBlockContentsForCompressionType
> 34.2 22.9% 63.4% 34.2 22.9%
ceph::buffer::create_aligned_in_mempool
> 11.9 7.9% 71.3% 12.1 8.1%
std::_Rb_tree::_M_emplace_hint_unique
> 10.7 7.1% 78.5% 71.2 47.7% rocksdb::ReadBlockContents
>
> Does it mean that most of RAM is used by rocksdb?
It looks like your heap dump is only accounting for 149.4MB of the
memory so probably not representative across the whole ~6.5G. Instead
could you try dumping the mempools via "ceph daemon osd.2969
dump_mempools"?
>
> How can I take a deeper look into memory usage ?
Beyond looking at the mempools, you can see the bluestore cache
allocation information by either enabling debug bluestore and debug
priority_cache_manager 5, or potentially looking at the PCM perf
counters (I'm not sure if those were in 14.2.12 though). Between the
heap data, mempool data, and priority cache records, it should become
clearer what's going on.
Mark
>
>
> Regards,
>
> Rafał Wądołowski
>
>
>
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