On 08/17/2015 07:03 AM, Alexandre DERUMIER wrote:
Hi,
Is this phenomenon normal?Is there any idea about this problem?
It's a known problem with tcmalloc (search on the ceph mailing).
starting osd with "TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES=128M" environnement variable should help.
Note that this only works if you use a version of gperftools/tcmalloc
newer than 2.1.
Another way, is to compile ceph with jemalloc instead tcmalloc (./configure --with-jemalloc ...)
Yep! At least from what I've seen so far, jemalloc is still a little
faster for 4k random writes even compared to tcmalloc with the patch +
128MB thread cache. Should have some data soon (mostly just a
reproduction of Sandisk and Intel's work).
----- Mail original -----
De: "YeYin" <eyniy@xxxxxx>
À: "ceph-users" <ceph-users@xxxxxxxxxxxxxx>
Envoyé: Lundi 17 Août 2015 11:58:26
Objet: tcmalloc use a lot of CPU
Hi, all,
When I do performance test with rados bench, I found tcmalloc consumed a lot of CPU:
Samples: 265K of event 'cycles', Event count (approx.): 104385445900
+ 27.58% libtcmalloc.so.4.1.0 [.] tcmalloc::CentralFreeList::FetchFromSpans()
+ 15.25% libtcmalloc.so.4.1.0 [.] tcmalloc::ThreadCache::ReleaseToCentralCache(tcmalloc::ThreadCache::FreeList*, unsigned long,
+ 12.20% libtcmalloc.so.4.1.0 [.] tcmalloc::CentralFreeList::ReleaseToSpans(void*)
+ 1.63% perf [.] append_chain
+ 1.39% libtcmalloc.so.4.1.0 [.] tcmalloc::CentralFreeList::ReleaseListToSpans(void*)
+ 1.02% libtcmalloc.so.4.1.0 [.] tcmalloc::CentralFreeList::RemoveRange(void**, void**, int)
+ 0.85% libtcmalloc.so.4.1.0 [.] 0x0000000000017e6f
+ 0.75% libtcmalloc.so.4.1.0 [.] tcmalloc::ThreadCache::IncreaseCacheLimitLocked()
+ 0.67% libc-2.12.so [.] memcpy
+ 0.53% libtcmalloc.so.4.1.0 [.] operator delete(void*)
Ceph version:
# ceph --version
ceph version 0.87.2 (87a7cec9ab11c677de2ab23a7668a77d2f5b955e)
Kernel version:
3.10.83
Is this phenomenon normal? Is there any idea about this problem?
Thanks.
Ye
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