Date: Tue, 13 Dec 2016 16:27:59 +1100 From: Peter Jeremy <peter@rulingia.com> To: Warner Losh <imp@bsdimp.com> Cc: Ed Schouten <ed@nuxi.nl>, FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Sysctl as a Service, or: making sysctl(3) more friendly for monitoring systems Message-ID: <20161213052759.GP61036@server.rulingia.com> In-Reply-To: <CANCZdfrjsLdMoZ9Eg19-mEbyxUefJxUmeq=cT_bagrJqzWnUOg@mail.gmail.com> References: <CABh_MKk87hJTsu1ETX8Ffq9E8gqRPELeSEKzf1jKk_wwUROgAw@mail.gmail.com> <eea0aa41-2bbc-0ddc-d951-f495c5ba2341@freebsd.org> <200A5D70-24CE-4843-B99D-E10A2AF4F68F@FreeBSD.org> <CABh_MKkAoTj4wA9oTz-fK0rokgMfuiUWpLt6t=qRXy6vvCh7rg@mail.gmail.com> <CANCZdfrjsLdMoZ9Eg19-mEbyxUefJxUmeq=cT_bagrJqzWnUOg@mail.gmail.com>
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--Md/poaVZ8hnGTzuv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2016-Dec-12 17:57:07 -0700, Warner Losh <imp@bsdimp.com> wrote: >On Mon, Dec 12, 2016 at 6:34 AM, Ed Schouten <ed@nuxi.nl> wrote: >> $ time ./prometheus_sysctl_exporter | wc -l >> 0.00 real 0.00 user 0.00 sys >> 3162 >> >> If our sysctl tree would get substantially larger at some point, we >> should of course revisit this. > >That sounds cool. I'd love to see what you came up with to get those resul= ts. I think that's impressive as well. >While we're here... there's one thing I'd love to see from a >hypothetical /dev/sysctl... When a sysctl value changes (or some >subset), I'd like it to appear on a read-channel. That way, I could >monitor temperature w/o needing to constantly poll for changes, for >example. That sounds like a job for kqueue(2), though it would need to be plumbed through. The biggest problem I see is that nothing in the sysctl mechanism has any way of reporting that a value has changed and so consumers of that data should re-check. This means that you'd probably just wind up polling in the kernel. Note that Prometheus is designed around regularly polling the systems it's monitoring so this sort of functionality wouldn't benefit it. --=20 Peter Jeremy --Md/poaVZ8hnGTzuv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQJ8BAEBCgBmBQJYT4beXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRFRUIyOTg2QzMwNjcxRTc0RTY1QzIyN0Ux NkE1OTdBMEU0QTIwQjM0AAoJEBall6Dkogs0dh0QAIvLQ91q08Bq0xEMXJpcA0uD A4aXZSZXVfIZ2yIn3hLXwdp7WJHfzpgoeYMhAuv1dq2fmEu4Yt9JyY1mus9FCPPP Q8AauacE+vp9MIYspdwTIC/47xBC6D+VjIxUbjgMhKwdXRgqEOt6dWnIAXgzvyCy osP/lp6p0meIsItM1ymF5QHijXuEi343Iy+J0inMeofzdj4C/Hk66QAJ58xMl6aJ pVE3g8UdCEpDwMTsz3+eM7OzUCr+/Pse0OUAYJfwj6kJiTjSK9WfEXLuhiLFg9JY sM1VFlA+R7387+EWdfvooQLm7NcgsaRdATtj2Y1V0MINRONf1pCN7PWV2a4JPvbn dhtejm1c1GWpTgswmyy/GrHedS1wGValcCKAWfWIjGV9e1iMXpIAcuTEr3gxYaML YNIoOFU4+ZudyHkgg7my4JtuTRv+3kbpq2tPqGoWpZuxqQ+gaYN20EdPgm39sTPg XXHiDaJYvJSDHwaQyzKADpDaeuN9PXNoZHhP1drs6RtY6s9+deeWFiegwT9KaEI1 SOAe8g1hgZNvlYuwsBbLy+dgqigwCVARnUpXoDQKyuHnt1L2Tc+mAohvVK38T/91 6rwkETOzNs6miDURJLlbxUE5wVPWN0/0+S9o2vNh4dvHYyCIDMxoDASIigYmcnTV d8hIo2kkvKhEGE6ioa7v =9J41 -----END PGP SIGNATURE----- --Md/poaVZ8hnGTzuv--
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