** Changed in: ceph (Ubuntu)
Status: Triaged => Won't Fix
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https://bugs.launchpad.net/bugs/1702777
Title:
ceph package is not built with jemalloc support
Status in ceph package in Ubuntu:
Won't Fix
Bug description:
For all-flash scenarios it makes sense to use jemalloc instead of
tcmalloc, see:
http://tracker.ceph.com/projects/ceph/wiki/Tuning_for_All_Flash_Deployments#Memory-Tuning
https://www.sebastien-han.fr/blog/2015/09/07/the-ceph-and-tcmalloc-performance-story/
https://software.intel.com/en-us/articles/using-intel-optane-and-
intel-3d-nand-technology-with-ceph-to-build-high-performance-cloud
I have seen other people asking about this for trusty and xenial:
https://www.spinics.net/lists/ceph-users/msg28010.html
https://www.spinics.net/lists/ceph-users/msg35221.html
However, our package is compiled only with tcmalloc:
https://git.launchpad.net/~ubuntu-server-
dev/ubuntu/+source/ceph/tree/debian/rules?h=ubuntu/xenial#n39
On a live system (no trace of jemalloc):
readelf -d `which ceph-osd` | grep malloc
0x0000000000000001 (NEEDED) Shared library: [libtcmalloc.so.4]
dpkg -l '*malloc*'
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=================================-=====================-=====================-========================================================================
ii libtcmalloc-minimal4 2.4-0ubuntu5.16.04.1 amd64 efficient thread-caching malloc
strings `which ceph-osd` | grep jemalloc ; echo $?
1
People may get confused with the fact that LD_PRELOAD will not result in jemalloc usage due to the fact that a package simply does not have that support compiled-in:
https://github.com/ceph/ceph/blob/jewel/etc/default/ceph
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Given the fact that NVMe (filestore journal or bluestore WAL) -> SSD
(data) or Optane (filestore journal or bluestore WAL) -> SSD (data)
setups are becoming more common, --with-jemalloc option should be
added to the list of compile flags.
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