Date: Mon, 18 Jun 2018 07:45:31 -0500 From: Adam <amvandemore@gmail.com> To: tech-lists <tech-lists@zyxst.net> Cc: "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: lightly loaded system eats swap space Message-ID: <CA%2BtpaK1hGsHLarvJ_1sEpjZ9bwL-zDNbnR%2BPX9BWOfNq6MXN_A@mail.gmail.com> In-Reply-To: <ab5d0cb0-13f5-5de8-6189-c0a5c621c6e9@zyxst.net> References: <c8277497-ffcf-0503-490b-96d1b4605af7@zyxst.net> <20180618160855.44d9a0c2.freebsd.ed.lists@sumeritec.com> <ab5d0cb0-13f5-5de8-6189-c0a5c621c6e9@zyxst.net>
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On Mon, Jun 18, 2018 at 7:27 AM, tech-lists <tech-lists@zyxst.net> wrote: > On 18/06/2018 09:08, Erich Dollansky wrote: > >> Hi, >> >> On Sun, 17 Jun 2018 23:19:02 +0100 >> tech-lists <tech-lists@zyxst.net> wrote: >> >> freebsd-11-stable r333874, ZFS raidz1-0 (3x4TB disks), 128GB RAM, >>> Swap: 4096M Total, 3502M Used, 594M Free, 85% Inuse >>> >> >> this might not be related but I noticed that your swap space is small >> compared to RAM size. I noticed on a much smaller Raspberry Pi, that it >> runs into trouble when there is no swap even there is enough RAM >> available. Is it easily possible for you to add some GB of swap space >> and let the machine run then? >> >> How much swap do the other machines have? >> > > Hi, > > Yes, the machine with the problem uses the default 4GB swap. That's all > the swap it has. The machine without issue has a swapfile installed on a > SSD in addition to the default 4GB swap. > > problematic machine: > Device 512-blocks Used Avail Capacity > /dev/ada0p3 8388608 3.3G 714M 83% > > machine without a problem, it has swapfile installed: > Device 512-blocks Used Avail Capacity > /dev/ada0s1b 8262248 1.7G 2.2G 44% > /dev/md0 65536000 1.9G 29G 6% > Total 73798248 3.7G 32G 10% > > I added the swapfile a long time ago on this machine due to the same issue. > > But my problem isn't so much an out of swapspace problem; all this is, is > a symptom. My problem is "why is it swapping out at all on a 128GB system > and why is what's swapped out not being swapped back in again". > What is the output of sysctl vm.overcommit? If this system is intended on being a VM host, then why don't you limit ARC to something reasonable like Total Mem - Projected VM Mem - Overhead = Ideal ARC . -- Adam
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