memory results of osd daemon under load, jemalloc use always more memory than tcmalloc, jemalloc 4.0 seem to reduce memory usage but still a little bit more than tcmalloc osd_op_threads=2 : tcmalloc 2.1 ------------------------------------------ root 38066 2.3 0.7 1223088 505144 ? Ssl 08:35 1:32 /usr/bin/ceph-osd --cluster=ceph -i 4 -f root 38165 2.4 0.7 1247828 525356 ? Ssl 08:35 1:34 /usr/bin/ceph-osd --cluster=ceph -i 5 -f osd_op_threads=32: tcmalloc 2.1 ------------------------------------------ root 39002 102 0.7 1455928 488584 ? Ssl 09:41 0:30 /usr/bin/ceph-osd --cluster=ceph -i 4 -f root 39168 114 0.7 1483752 518368 ? Ssl 09:41 0:30 /usr/bin/ceph-osd --cluster=ceph -i 5 -f osd_op_threads=2 jemalloc 3.5 ----------------------------- root 18402 72.0 1.1 1642000 769000 ? Ssl 09:43 0:17 /usr/bin/ceph-osd --cluster=ceph -i 0 -f root 18434 89.1 1.2 1677444 797508 ? Ssl 09:43 0:21 /usr/bin/ceph-osd --cluster=ceph -i 1 -f osd_op_threads=32 jemalloc 3.5 ----------------------------- root 17204 3.7 1.2 2030616 816520 ? Ssl 08:35 2:31 /usr/bin/ceph-osd --cluster=ceph -i 0 -f root 17228 4.6 1.2 2064928 830060 ? Ssl 08:35 3:05 /usr/bin/ceph-osd --cluster=ceph -i 1 -f osd_op_threads=2 jemalloc 4.0 ----------------------------- root 19967 113 1.1 1432520 737988 ? Ssl 10:04 0:31 /usr/bin/ceph-osd --cluster=ceph -i 1 -f root 19976 93.6 1.0 1409376 711192 ? Ssl 10:04 0:26 /usr/bin/ceph-osd --cluster=ceph -i 0 -f osd_op_threads=32 jemalloc 4.0 ----------------------------- root 20484 128 1.1 1689176 778508 ? Ssl 10:06 0:26 /usr/bin/ceph-osd --cluster=ceph -i 0 -f root 20502 170 1.2 1720524 810668 ? Ssl 10:06 0:35 /usr/bin/ceph-osd --cluster=ceph -i 1 -f ----- Mail original ----- De: "aderumier" <aderumier@xxxxxxxxx> À: "Shinobu Kinjo" <skinjo@xxxxxxxxxx> Cc: "Stephen L Blinick" <stephen.l.blinick@xxxxxxxxx>, "Somnath Roy" <Somnath.Roy@xxxxxxxxxxx>, "Mark Nelson" <mnelson@xxxxxxxxxx>, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Jeudi 20 Août 2015 07:29:22 Objet: Re: Ceph Hackathon: More Memory Allocator Testing Hi, jemmaloc 4.0 has been released 2 days agos https://github.com/jemalloc/jemalloc/releases I'm curious to see performance/memory usage improvement :) ----- Mail original ----- De: "Shinobu Kinjo" <skinjo@xxxxxxxxxx> À: "Stephen L Blinick" <stephen.l.blinick@xxxxxxxxx> Cc: "aderumier" <aderumier@xxxxxxxxx>, "Somnath Roy" <Somnath.Roy@xxxxxxxxxxx>, "Mark Nelson" <mnelson@xxxxxxxxxx>, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Jeudi 20 Août 2015 04:00:15 Objet: Re: Ceph Hackathon: More Memory Allocator Testing How about making any sheet for testing patter? Shinobu ----- Original Message ----- From: "Stephen L Blinick" <stephen.l.blinick@xxxxxxxxx> To: "Alexandre DERUMIER" <aderumier@xxxxxxxxx>, "Somnath Roy" <Somnath.Roy@xxxxxxxxxxx> Cc: "Mark Nelson" <mnelson@xxxxxxxxxx>, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Sent: Thursday, August 20, 2015 10:09:36 AM Subject: RE: Ceph Hackathon: More Memory Allocator Testing Would it make more sense to try this comparison while changing the size of the worker thread pool? i.e. changing "osd_op_num_threads_per_shard" and "osd_op_num_shards" (default is currently 2 and 5 respectively, for a total of 10 worker threads). Thanks, Stephen -----Original Message----- From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of Alexandre DERUMIER Sent: Wednesday, August 19, 2015 11:47 AM To: Somnath Roy Cc: Mark Nelson; ceph-devel Subject: Re: Ceph Hackathon: More Memory Allocator Testing Just have done a small test with jemalloc, change osd_op_threads value, and check the memory just after daemon restart. osd_op_threads = 2 (default) USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 10246 6.0 0.3 1086656 245760 ? Ssl 20:36 0:01 /usr/bin/ceph-osd --cluster=ceph -i 0 -f osd_op_threads = 32 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 10736 19.5 0.4 1474672 307412 ? Ssl 20:37 0:01 /usr/bin/ceph-osd --cluster=ceph -i 0 -f I'll try to compare with tcmalloc tommorow and under load. ----- Mail original ----- De: "Somnath Roy" <Somnath.Roy@xxxxxxxxxxx> À: "aderumier" <aderumier@xxxxxxxxx> Cc: "Mark Nelson" <mnelson@xxxxxxxxxx>, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Mercredi 19 Août 2015 19:29:56 Objet: RE: Ceph Hackathon: More Memory Allocator Testing Yes, it should be 1 per OSD... There is no doubt that TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES is relative to the number of threads running.. But, I don't know if number of threads is a factor for jemalloc.. Thanks & Regards Somnath -----Original Message----- From: Alexandre DERUMIER [mailto:aderumier@xxxxxxxxx] Sent: Wednesday, August 19, 2015 9:55 AM To: Somnath Roy Cc: Mark Nelson; ceph-devel Subject: Re: Ceph Hackathon: More Memory Allocator Testing << I think that tcmalloc have a fixed size (TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES), and share it between all process. >>I think it is per tcmalloc instance loaded , so, at least with num_osds * num_tcmalloc_instance * TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES in a box. What is num_tcmalloc_instance ? I think 1 osd process use a defined TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES size ? I'm saying that, because I have exactly the same bug, client side, with librbd + tcmalloc + qemu + iothreads. When I defined too much iothread threads, I'm hitting the bug directly. (can reproduce 100%). Like the thread_cache size is divide by number of threads? ----- Mail original ----- De: "Somnath Roy" <Somnath.Roy@xxxxxxxxxxx> À: "aderumier" <aderumier@xxxxxxxxx>, "Mark Nelson" <mnelson@xxxxxxxxxx> Cc: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Mercredi 19 Août 2015 18:27:30 Objet: RE: Ceph Hackathon: More Memory Allocator Testing << I think that tcmalloc have a fixed size (TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES), and share it between all process. I think it is per tcmalloc instance loaded , so, at least with num_osds * num_tcmalloc_instance * TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES in a box. Also, I think there is no point of increasing osd_op_threads as it is not in IO path anymore..Mark is using default 5:2 for shard:thread per shard.. But, yes, it could be related to number of threads OSDs are using, need to understand how jemalloc works..Also, there may be some tuning to reduce memory usage (?). Thanks & Regards Somnath -----Original Message----- From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of Alexandre DERUMIER Sent: Wednesday, August 19, 2015 9:06 AM To: Mark Nelson Cc: ceph-devel Subject: Re: Ceph Hackathon: More Memory Allocator Testing I was listening at the today meeting, and seem that the blocker to have jemalloc as default, is that it's used more memory by osd (around 300MB?), and some guys could have boxes with 60disks. I just wonder if the memory increase is related to osd_op_num_shards/osd_op_threads value ? Seem that as hackaton, the bench has been done on super big cpus boxed 36cores/72T, http://ceph.com/hackathon/2015-08-ceph-hammer-full-ssd.pptx with osd_op_threads = 32. I think that tcmalloc have a fixed size (TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES), and share it between all process. Maybe jemalloc allocated memory by threads. (I think guys with 60disks box, dont use ssd, so low iops by osd, and they don't need a lot of threads by osd) ----- Mail original ----- De: "aderumier" <aderumier@xxxxxxxxx> À: "Mark Nelson" <mnelson@xxxxxxxxxx> Cc: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Mercredi 19 Août 2015 16:01:28 Objet: Re: Ceph Hackathon: More Memory Allocator Testing Thanks Marc, Results are matching exactly what I have seen with tcmalloc 2.1 vs 2.4 vs jemalloc. and indeed tcmalloc, even with bigger cache, seem decrease over time. What is funny, is that I see exactly same behaviour client librbd side, with qemu and multiple iothreads. Switching both server and client to jemalloc give me best performance on small read currently. ----- Mail original ----- De: "Mark Nelson" <mnelson@xxxxxxxxxx> À: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Mercredi 19 Août 2015 06:45:36 Objet: Ceph Hackathon: More Memory Allocator Testing Hi Everyone, One of the goals at the Ceph Hackathon last week was to examine how to improve Ceph Small IO performance. Jian Zhang presented findings showing a dramatic improvement in small random IO performance when Ceph is used with jemalloc. His results build upon Sandisk's original findings that the default thread cache values are a major bottleneck in TCMalloc 2.1. To further verify these results, we sat down at the Hackathon and configured the new performance test cluster that Intel generously donated to the Ceph community laboratory to run through a variety of tests with different memory allocator configurations. I've since written the results of those tests up in pdf form for folks who are interested. The results are located here: http://nhm.ceph.com/hackathon/Ceph_Hackathon_Memory_Allocator_Testing.pdf I want to be clear that many other folks have done the heavy lifting here. These results are simply a validation of the many tests that other folks have already done. Many thanks to Sandisk and others for figuring this out as it's a pretty big deal! Side note: Very little tuning other than swapping the memory allocator and a couple of quick and dirty ceph tunables were set during these tests. It's quite possible that higher IOPS will be achieved as we really start digging into the cluster and learning what the bottlenecks are. 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