Date: Sat, 6 Jan 2024 13:02:26 +0100 From: "Patrick M. Hausen" <hausen@punkt.de> To: Garrett Wollman <wollman@bimajority.org> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: Odd values for various memory metrics via SNMP Message-ID: <E1BABD9C-C243-4949-8F69-152B4E23A8CB@punkt.de> In-Reply-To: <25996.34932.339497.605798@hergotha.csail.mit.edu> References: <1EDAF2AC-3A2B-43BE-B66B-E095F5A80C2C@punkt.de> <de2988a0-00d6-4b4b-8150-bfa235649d64@aetern.org> <84B7C7D7-BC06-4944-A7E0-5AFC47B6BC0E@punkt.de> <8f4cf72e-8320-4bfd-a4d9-3db34db4580d@aetern.org> <A09B8144-EC0A-42DD-AAD6-D3C1E7FDFEB9@punkt.de> <25996.34932.339497.605798@hergotha.csail.mit.edu>
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Hi all, > Am 27.12.2023 um 21:26 schrieb Garrett Wollman = <wollman@bimajority.org>: >=20 > <<On Tue, 19 Dec 2023 20:16:38 +0100, "Patrick M. Hausen" = <hausen@punkt.de> said: >=20 >> Now only "virtual memory" is left - according to the book that should = be >> the sum of physical memory and swap space - and for my single Linux >> host it is. >=20 >> For the FreeBSD systems this is the one left that still looks = nonsensical. >=20 >> OPNsense (8G RAM, 8G swap): 4.91 of 4.99G used. >> TrueNAS (64G RAM, 32G swap): 627 of 628G used. >> TrueNAS 2 (32G RAM, 32G swap): 512 of 516G used. >=20 > This is computed by the function vmtotal() in sys/vm/vm_meter.c. It > walks all VM objects in the system, skipping those that are > unreferenced, and adds up all of their sizes. There is one VM object > for every open file and every running executable, shared library, and > mmap()ed region, plus one for every copy-on-write mapping for each > process that has modified it, which includes the data segment of every > executable and shared library. This has no connection to either > physical memory or swap space. Why does FreeBSD calculate the values this way while MWL's book clearly states differently? Who's wrong here? Browsing the host resources MIB I can only find the syntactical = definition of the hrStorage subtree but nowhere was I able to find a definitive = documentation on the semantics what certain entries like "virtual memory" are supposed = to mean? I'll go ask MWL where he got what he wrote in his book, but I'm still = confused. There must be some standard for meaningful values, right? Kind regards, Patrick --=20 punkt.de GmbH Patrick M. Hausen .infrastructure Sophienstr. 187 76185 Karlsruhe Tel. +49 721 9109500 https://infrastructure.punkt.de info@punkt.de AG Mannheim 108285 Gesch=C3=A4ftsf=C3=BChrer: Daniel Lienert, Fabian Stein
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