Date: Tue, 13 Dec 2016 16:08:16 +0100 From: Ed Schouten <ed@nuxi.nl> To: Warner Losh <imp@bsdimp.com> Cc: Jonathan Anderson <jonathan@freebsd.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org>, Allan Jude <allanjude@freebsd.org> Subject: Re: Sysctl as a Service, or: making sysctl(3) more friendly for monitoring systems Message-ID: <CABh_MK=jrpZCqgFmy-AB0VhVBp_cTDT468zsYe%2Btjmbub=PiMA@mail.gmail.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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Hi Warner, 2016-12-13 1:57 GMT+01:00 Warner Losh <imp@bsdimp.com>: > 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. Yes, that would be nice to have. Unfortunately, Prometheus is mostly pull-based, so I guess such a feature wouldn't be needed in this case. Anyway, I just finished implementing support for attaching labels to sysctl nodes: https://reviews.freebsd.org/D8775 This patch is slightly different from what I had envisioned. For example, to translate this sysctl: hw.acpi.thermal.tz1.temperature to: sysctl_hw_acpi_thermal_temperature_celcius{thermal_zone="tz1"} my idea was to attach a "thermal_zone" label to the hw.acpi.thermal node, indicating that the names of its children should be interpreted a value for that label. Unfortunately, hw.acpi.thermal also has some children that should not have that label attached: hw.acpi.thermal.user_override hw.acpi.thermal.polling_rate hw.acpi.thermal.min_runtime That's why I went for an approach where the label is attached to hw.acpi.thermal.tz1, so that labelling can be controlled more granularly. Note that this change does not affect existing use of sysctl at all. It's merely the case that they now have additional metadata that is only used by the Prometheus exporter. -- Ed Schouten <ed@nuxi.nl> Nuxi, 's-Hertogenbosch, the Netherlands KvK-nr.: 62051717
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