Date: Thu, 1 Sep 2022 16:36:44 -0700 From: David Wolfskill <david@catwhisker.org> To: hackers@freebsd.org Subject: Reasonable/sane limits for kern.msgbufsize? Message-ID: <YxFCDGCRmoXpDJn/@albert.catwhisker.org> Resent-Message-ID: <YxFCyfAzXJyxIW5q@albert.catwhisker.org>
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--RuaTJOZqeFO4W2mx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Empirically, I have found that for dmesg.boot to contain the full dmesg =66rom a verbose boot on one of my machines, starting from: ---<<BOOT>>--- APIC: Using the MADT enumerator. Copyright (c) 1992-2021 The FreeBSD Project. =2E.. I need to increase kern.msgbufsize to above 200KiB (204800); so far, 262144 (256KiB) seems to work for stable/12. (Actual size of /var/run/dmesg.boot just now was 216929 -- 212KiB.) Note that the default value is 96KiB (98304). In this particular case, the machine has 256GiB RAM -- but kernel address space (I expect) remains a constrained resource. How much trouble am I asking for if I set kern.msgbufsize=3D262144 in /boot/laoder.conf? It might be cool to be able to do that only for a verbose boot, and have a somewhat more reasonable value for a non-verbose boot.... [Rationale: I build FreeBSD often -- tracking head, stable/13 and (currently) stable/12 daily. I place salient information on a Web site; that includes a copy of /var/run/dmesg.boot -- from a verbose boot. But I noted a while back that much of the first part of the latter was missing; I only found out "how much" a few minutes ago.] Peace, david --=20 David H. Wolfskill david@catwhisker.org See "Truth Social"? Read it as "Pravda" -- and adjust expectations accordi= ngly. See https://www.catwhisker.org/~david/publickey.gpg for my public key. --RuaTJOZqeFO4W2mx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iNUEARYKAH0WIQSr0Kzv+UJRY3wfOii0+6PfV4Ix1AUCYxFCDF8UgAAAAAAuAChp c3N1ZXItZnByQG5vdGF0aW9ucy5vcGVucGdwLmZpZnRoaG9yc2VtYW4ubmV0QUJE MEFDRUZGOTQyNTE2MzdDMUYzQTI4QjRGQkEzREY1NzgyMzFENAAKCRC0+6PfV4Ix 1Hu+AP4gw5agBu/cxC8BJEXbMzoT8ZGkbCt3JFYPVGKa/x5AtgEA3gXfX9oAb8Qj bXKCc9GF1tmb+fQySp92HEkbS7xmZgQ= =bf91 -----END PGP SIGNATURE----- --RuaTJOZqeFO4W2mx--
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