I'm thinking if this can be malloc() not returning memory to the system after peak loads: *"Occasionally, free can actually return memory to the operating system and make the process smaller. Usually, all it can do is allow a later call to malloc to reuse the space. In the meantime, the space remains in your program as part of a free-list used internally by malloc." [1]*
Does it sound sane? If yes, what would be a best way to check that? [1] http://www.gnu.org/software/libc/manual/pdf/libc.pdf Thanks, Oleg On Wed, Mar 6, 2019 at 12:34 PM Oleg Bondarev <obonda...@mirantis.com> wrote: > Hi, > > On Wed, Mar 6, 2019 at 1:08 AM Ben Pfaff <b...@ovn.org> wrote: > >> Starting from 0x30, this looks like a "minimatch" data structure, which >> is a kind of compressed bitwise match against a flow. >> >> 00000030: 0000 0000 0000 4014 0000 0000 0000 0000 >> 00000040: 0000 0000 0000 0000 fa16 3e2b c5d5 0000 0000 0022 0000 0000 >> >> 00000058: 0000 0000 0000 4014 0000 0000 0000 0000 >> 00000068: 0000 0000 ffff ffff ffff ffff ffff 0000 0000 0fff 0000 0000 >> >> I think this corresponds to a flow of this form: >> >> >> pkt_mark=0xc5d5/0xffff,skb_priority=0x3e2bfa16,reg13=0,mpls_label=2,mpls_tc=1,mpls_ttl=0,mpls_bos=0 >> >> Is that at all meaningful? Does it match anything that appears in the >> OpenFlow flow table? >> > > Not sure, actually fa:16:3e:2b:c5:d5 is a mac address of a neutron port > (this is an OpenStack cluster) - the port is a VM port. > fa:16:3e/fa:16:3f - are standard neutron mac prefixes. That makes me think > those might be some actual eth packets (broadcasts?) that somehow > stuck in memory.. > So I didn't find anything similar in the flow tables. I'm attaching flows > of all 5 OVS bridges on the node. > > >> >> Are you using the kernel or DPDK datapath? >> > > It's kernel datapath, no DPDK. Ubuntu with 4.13.0-45 kernel. > > >> >> On Tue, Mar 05, 2019 at 08:42:14PM +0400, Oleg Bondarev wrote: >> > Hi, >> > >> > thanks for your help! >> > >> > On Tue, Mar 5, 2019 at 7:26 PM Ben Pfaff <b...@ovn.org> wrote: >> > >> > > You're talking about the email where you dumped out a repeating >> sequence >> > > from some blocks? That might be the root of the problem, if you can >> > > provide some more context. I didn't see from the message where you >> > > found the sequence (was it just at the beginning of each of the 4 MB >> > > blocks you reported separately, or somewhere else), how many copies of >> > > it, or if you were able to figure out how long each of the blocks was. >> > > If you can provide that information I might be able to learn some >> > > things. >> > > >> > >> > Yes, those were beginnings of 0x4000000 size blocks reported by the >> script. >> > I also checked 0x8000000 blocks reported and the content is the same. >> > Examples of how those blocks end: >> > - https://pastebin.com/D9M6T2BA >> > - https://pastebin.com/gNT7XEGn >> > - https://pastebin.com/fqy4XDbN >> > >> > So basically contents of the blocks are sequences of: >> > >> > *00000020: 0000 0000 0000 0000 6500 0000 0000 0000 ........e.......* >> > *00000030: 0000 0000 0000 4014 0000 0000 0000 0000 ......@.........* >> > *00000040: 0000 0000 0000 0000 fa16 3e2b c5d5 0000 ..........>+....* >> > *00000050: 0000 0022 0000 0000 0000 0000 0000 4014 ..."..........@.* >> > *00000060: 0000 0000 0000 0000 0000 0000 ffff ffff ................* >> > *00000070: ffff ffff ffff 0000 0000 0fff 0000 0000 ................* >> > >> > following each other and sometimes separated by sequences like this: >> > >> > *00001040: 6861 6e64 6c65 7232 3537 0000 0000 0000 handler257......* >> > >> > I ran the scripts against several core dumps of several compute nodes >> with >> > the issue and >> > the picture is pretty much the same: 0x4000000 blocks and less 0x8000000 >> > blocks. >> > I checked the core dump from a compute node where OVS memory consumption >> > was ok: >> > no such block sizes reported. >> > >> > >> > > >> > > On Tue, Mar 05, 2019 at 09:07:55AM +0400, Oleg Bondarev wrote: >> > > > Hi Ben, >> > > > >> > > > I didn't have a chance to debug the scripts yet, but just in case >> you >> > > > missed my last email with examples of repeatable blocks >> > > > and sequences - do you think we still need to analyze further, will >> the >> > > > scripts tell more about the heap? >> > > > >> > > > Thanks, >> > > > Oleg >> > > > >> > > > On Thu, Feb 28, 2019 at 10:14 PM Ben Pfaff <b...@ovn.org> wrote: >> > > > >> > > > > On Tue, Feb 26, 2019 at 01:41:45PM +0400, Oleg Bondarev wrote: >> > > > > > Hi, >> > > > > > >> > > > > > thanks for the scripts, so here's the output for a 24G core >> dump: >> > > > > > https://pastebin.com/hWa3R9Fx >> > > > > > there's 271 entries of 4MB - does it seem something we should >> take a >> > > > > closer >> > > > > > look at? >> > > > > >> > > > > I think that this output really just indicates that the script >> failed. >> > > > > It analyzed a lot of regions but didn't output anything useful. >> If it >> > > > > had worked properly, it would have told us a lot about data >> blocks that >> > > > > had been allocated and freed. >> > > > > >> > > > > The next step would have to be to debug the script. It definitely >> > > > > worked for me before, because I have fixed at least 3 or 4 bugs >> based >> > > on >> > > > > it, but it also definitely is a quick hack and not something that >> I can >> > > > > stand behind. I'm not sure how to debug it at a distance. It >> has a >> > > > > large comment that describes what it's trying to do. Maybe that >> would >> > > > > help you, if you want to try to debug it yourself. I guess it's >> also >> > > > > possible that glibc has changed its malloc implementation; if so, >> then >> > > > > it would probably be necessary to start over and build a new >> script. >> > > > > >> > > >> >
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