From nobody Tue Nov 22 15:49:29 2022 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4NGpbf05D4z4hwdw for ; Tue, 22 Nov 2022 15:49:34 +0000 (UTC) (envelope-from mike@karels.net) Received: from mail.karels.net (mail.karels.net [216.160.39.52]) by mx1.freebsd.org (Postfix) with ESMTP id 4NGpbd44Jcz3D6y for ; Tue, 22 Nov 2022 15:49:33 +0000 (UTC) (envelope-from mike@karels.net) Authentication-Results: mx1.freebsd.org; none Received: from mail.karels.net (localhost [127.0.0.1]) by mail.karels.net (8.16.1/8.16.1) with ESMTP id 2AMFnTc6077416; Tue, 22 Nov 2022 09:49:29 -0600 (CST) (envelope-from mike@karels.net) Received: from [10.0.2.130] ([10.0.1.1]) by mail.karels.net with ESMTPSA id EN2XNYnvfGNmLgEA4+wvSQ (envelope-from ); Tue, 22 Nov 2022 09:49:29 -0600 From: Mike Karels To: Dan Mack Cc: Warner Losh , freebsd-current@freebsd.org Subject: Re: dmesg content lifetime Date: Tue, 22 Nov 2022 09:49:29 -0600 X-Mailer: MailMate (1.14r5921) Message-ID: <21FB93B6-708F-4E69-B482-C7601C15394A@karels.net> In-Reply-To: <6146841c-baef-134-dcd9-30db2d92732@macktronics.com> References: <9d519f-ce87-72d-dc6-789817468974@macktronics.com> <6146841c-baef-134-dcd9-30db2d92732@macktronics.com> List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 4NGpbd44Jcz3D6y X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:209, ipnet:216.160.36.0/22, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-ThisMailContainsUnwantedMimeParts: N On 22 Nov 2022, at 9:34, Dan Mack wrote: > It disappears a piece at a time - the oldest entries disappear first. H= owever, it vanishes even when there are only 2-3 lines in it so I didn't = think capacity was in play as I expected. > > So for example I might see a rate-limit entry from someone spamming the= system and then it will usually be gone in a couple days and the buffer = is completely empty. Similarly if I do something like ifconfig em0 down= ; ifconfig em0 up ; it's logged but disappears after a day or so. > > I'm looking to see if this is just a cron job or something clearing it = as it might be user-error on my part. Also this is an older system so I= 'll probably look at it again after I update. I noticed this too, but discovered with =E2=80=9Cdmesg -a=E2=80=9D that t= he buffer was full of syslog messages, so dmesg without -a showed nothing. It seems unfortunate that syslog messages logged in the message buffer, a= t least once syslogd is running. Apparently this happens because they are output to /dev/console. Mike > Thank you, > > Dan > > > On Tue, 22 Nov 2022, Warner Losh wrote: > >> On Tue, Nov 22, 2022 at 8:13 AM Dan Mack wrote:= >> >>> It seems like dmesg content ages out over time. Is there a way to l= eave >>> the contents based on a fixed memory size instead? >>> >> >> It already is a fixed memory size. Do you see it all disappear at once= , or >> over time? >> >> Warner >>