Date: Mon, 26 Oct 2015 11:56:47 -0400 From: Allan Jude <allanjude@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: vmtotal consumes significant portion of cpu cycles Message-ID: <562E4D3F.8080204@freebsd.org> In-Reply-To: <CAHNYxxOWqAZxt%2BZcjU_JnUhE5n7%2BCbwv-_6yTOy1bOaYS=Z4gw@mail.gmail.com> References: <CAHNYxxOWqAZxt%2BZcjU_JnUhE5n7%2BCbwv-_6yTOy1bOaYS=Z4gw@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
[-- Attachment #1 --] On 2015-10-26 09:28, Jia-Shiun Li wrote: > Hi all, > > I noticed that 'sysctl -vm 1' consumes about 5% cpu time on a machine with > 2x 6-core Xeon E5v3 and 64GB memory. That's a lot for a monitoring tool. > > After digging a while I found that it is vmtotal() in kernel that consumes > major cycles. When memory usage is high the cost of vmtotal() rises too. It > is reproducible with sysctl when memory utilization is high: > > % time repeat 100 sysctl vm.vmtotal > /dev/null > 0.055u 8.102s 0:08.19 99.5% 31+175k 0+0io 0pf+0w > > % top > last pid: 40272; load averages: 0.32, 4.74, 8.01 up 3+01:19:54 > 17:23:59 > 58 processes: 1 running, 57 sleeping > CPU: 0.1% user, 0.0% nice, 1.6% system, 0.1% interrupt, 98.3% idle > Mem: 4509M Active, 52G Inact, 2819M Wired, 1572M Buf, 2930M Free > Swap: 3598M Total, 3598M Free > > PID USERNAME THR PRI NICE SIZE RES STATE C TIME CPU > COMMAND > 46841 root 30 20 0 9248M 7930M kqread 9 20.8H 11.88% bhyve > 49914 jsli 1 23 0 19320K 3884K select 5 134:08 4.79% systat > > > In FreeBSD source tree systat and vmstat are major user. Other tools like > bsnmpd may use it too via sysctl. > > I don't have idea yet how this can be improved. Shall I create a bug to > keep track of it? > > > -Jia-Shiun > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > In the first 2 references you say 'sysctl', do you mean 'systat' in all instances? -- Allan Jude [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) iQIcBAEBAgAGBQJWLk1CAAoJEBmVNT4SmAt+Lb0QAI5UjbsmNPLso7XGNTZenMLR yFGdVMdNYq+AcjP32PlKWUDrqdu/psHRgadX3PEpCrHZyfvaJUf7d7avzMK4/c7+ lLV953fn8B1ZWm4H45Paa7rG7UUB5Lj5iEhdQiCeP/WC1O5YbW6o1s2iOhL1E6fE uwIqO3v7wLTz48cRKAWnNRP3TxaB3NO/DroEMI5N8/IaQFV2yFS/oeue9TSo89lN j92E+9n6aOlJIYbWb0n+20F4m6H7pEB8dpCLcSi63J+kLjU15HHgk/M7lkf3Au7t lkbASff7xTnEs7R5dZZxtoZX1i0CWyl2YR3CoYr9gOcmeBTxCkd/OZyvnOx5yjed ziCQwCfi5oois/2flL4xQBydRg1ACVXNShWvTC9w/BvbR/FAoipOik2Rv0XP4dJJ cC02uBcFzJv605EPvlxCA9w0xk/QlbbuAdecduRrUm8QLTuV+g3AXUb4RTkbS/SA DUlmXub3EsyrRPCVsf+eOuVwMlvkvg7itD810MATnUG8dyPPsc3BffmPR2uIf9d7 7PP7QvWG7dKcwOc95+CXHaM3Z24eqBBFgBPt9ycLcaLQ6DDvecQKGv/XqtBZoi6P QTe1rjRD2+cKlMBQXCC+Te94evChsUvdkL0/3S00LprYQoB6YZPkJdSDEaiJDOX+ BDPUnHE/lK+YqnrptAx5 =JsuQ -----END PGP SIGNATURE-----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?562E4D3F.8080204>