Date: Mon, 08 Jan 2018 18:41:20 -0500 From: Michael Jung <mikej@mikej.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org, owner-freebsd-current@freebsd.org Subject: Re: witness_lock_list_get: witness exhausted Message-ID: <54018b1b2feaab3b05d7ed406eb8273c@mikej.com> In-Reply-To: <1684681.MCyL5Ev91y@ralph.baldwin.cx> References: <6eecc842ba7a37af6b2ffe146dfd91da@mikej.com> <1684681.MCyL5Ev91y@ralph.baldwin.cx>
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On 2018-01-08 13:39, John Baldwin wrote: > On Tuesday, November 28, 2017 02:46:03 PM Michael Jung wrote: >> Hi! >> >> I've recently up'd my processor count on our poudriere box and have >> started noticing the error >> "witness_lock_list_get: witness exhausted" on the console. The kernel >> *DOES NOT* crash but I >> thought the report may be useful to someone. >> >> $ uname -a >> FreeBSD poudriere 12.0-CURRENT FreeBSD 12.0-CURRENT #1 r325999: Sun >> Nov >> 19 18:41:20 EST 2017 >> mikej@poudriere:/usr/obj/usr/src/amd64.amd64/sys/GENERIC amd64 >> >> The machine is pretty busy running four poudriere build instances. >> >> last pid: 76584; load averages: 115.07, 115.96, 98.30 >> >> up 6+07:32:59 14:44:03 >> 763 processes: 117 running, 581 sleeping, 2 zombie, 63 lock >> CPU: 59.0% user, 0.0% nice, 40.7% system, 0.1% interrupt, 0.1% idle >> Mem: 12G Active, 2003M Inact, 44G Wired, 29G Free >> ARC: 28G Total, 11G MFU, 16G MRU, 122M Anon, 359M Header, 1184M Other >> 25G Compressed, 32G Uncompressed, 1.24:1 Ratio >> >> Let me know what additional information I might supply. > > This just means that WITNESS stopped working because it ran out of > pre-allocated objects. In particular the objects used to track how > many locks are held by how many threads: > > /* > * XXX: This is somewhat bogus, as we assume here that at most 2048 > threads > * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should > * probably be safe for the most part, but it's still a SWAG. > */ > #define LOCK_NCHILDREN 5 > #define LOCK_CHILDCOUNT 2048 > > Probably the '2048' (max number of concurrent threads) needs to scale > with > MAXCPU. 2048 threads is probably a bit low on big x86 boxes. Thank you for you explanation. We are expanding our ESXi cluster and even though with standard edition I can only assign 64 vCPU's to a guest and as much RAM as I want, I do like to help with edge cases if I can make them occur pushing boundaries as I can towards additianional improvements in FreeBSD. --mikej
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