Date: Mon, 18 Jun 2018 08:23:21 -0400 From: David Fullard <dave+freebsd@fullard.ca> To: freebsd-stable@freebsd.org Subject: Re: lightly loaded system eats swap space Message-ID: <1529324601.427299.1411679552.7868D498@webmail.messagingengine.com> In-Reply-To: <c8277497-ffcf-0503-490b-96d1b4605af7@zyxst.net> References: <c8277497-ffcf-0503-490b-96d1b4605af7@zyxst.net>
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I've noticed you've got a rather large ZFS ARC. You could try limiting the ZFS max ARC size by setting the vfs.zfs.arc_max sysctl. On Sun, Jun 17, 2018, at 6:19 PM, tech-lists wrote: > Hello list, > > context is (server) > freebsd-11-stable r333874, ZFS raidz1-0 (3x4TB disks), 128GB RAM, > E5-2630 @2.3GHz, generic kernel. > > There's one bhyve guest on this server (using 4x cpu and 16GB RAM, also > freebsd-11-stable) > > There have been no special options for zfs configuration on the server, > apart from several datasets having the compressed property set (lz4). > > The server runs nothing else really apart from sshd and it uses ntpd to > sync local time. > > How come such a lightly loaded server with plenty of resources is eating > up swap? If I run two bhyve instances, i.e. two of the same size as > indicated above, so 32GB used for the bhyves, I'll get out-of-swapspace > errors in the daily logs: > > +swap_pager_getswapspace(24): failed > +swap_pager_getswapspace(24): failed > +swap_pager_getswapspace(24): failed > > Here's top, with one bhyve instance running: > > last pid: 49494; load averages: 0.12, 0.13, 0.88 > > > up 29+11:36:06 22:52:45 > 54 processes: 1 running, 53 sleeping > CPU: 0.4% user, 0.0% nice, 0.4% system, 0.3% interrupt, 98.9% idle > Mem: 8664K Active, 52M Inact, 4797M Laundry, 116G Wired, 1391M Buf, > 4123M Free > ARC: 108G Total, 1653M MFU, 105G MRU, 32K Anon, 382M Header, 632M Other > 103G Compressed, 104G Uncompressed, 1.00:1 Ratio > Swap: 4096M Total, 3502M Used, 594M Free, 85% Inuse > > PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU > COMMAND > 49491 root 1 4 0 16444K 12024K select 9 0:12 6.49% ssh > 32868 root 12 20 0 9241M 4038M kqread 2 23.2H 1.30% bhyve > 49490 root 1 20 0 10812K 6192K sbwait 5 0:02 0.88% sftp > > From the looks of it, a huge amount of ram is wired. Why is that, and > how would I debug it? > > A server of similar spec which is running freebsd-current with seven > bhyve instances doesn't have this issue: > > last pid: 41904; load averages: 0.26, 0.19, 0.15 > > > up 17+01:06:11 23:14:13 > 27 processes: 1 running, 26 sleeping > CPU: 0.1% user, 0.0% nice, 0.3% system, 0.0% interrupt, 99.6% idle > Mem: 17G Active, 6951M Inact, 41G Laundry, 59G Wired, 1573M Buf, 1315M Free > ARC: 53G Total, 700M MFU, 52G MRU, 512K Anon, 182M Header, 958K Other > 53G Compressed, 69G Uncompressed, 1.30:1 Ratio, 122M Overhead > Swap: 35G Total, 2163M Used, 33G Free, 6% Inuse > > thanks, > -- > J. > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
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