Date: Fri, 27 Jul 2018 18:53:32 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 229670] ZFS ARC limit vfs.zfs.arc_max from /boot/loader.conf is not respected Message-ID: <bug-229670-227-gg559shwUi@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-229670-227@https.bugs.freebsd.org/bugzilla/> References: <bug-229670-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D229670 --- Comment #13 from Leif Pedersen <leif@ofWilsonCreek.com> --- So I looked back at this today, and I found that even after having returned maxvnodes to the default, I still see it overrunning arc_max persistently by almost 2x. I can lower maxvnodes below the default (179499), and then arc_m= ax is respected. Below are stats on the same system which has 6GB of RAM with arc_max set to 256MB, starting with maxvnodes at the default and then lower= ing it. Granted, one can reasonably argue that anyone capable of tinkering with arc= _max should be capable of tinkering with maxvnodes also. However, it is rather astonishing since there are suggestions to crank up maxvnodes to improve performance [wiki/ZFSTuningGuide] and to lower arc_max for small systems, b= ut no mention of one affecting the other. So I'm adding this data to be of hel= p if this is considered a significant bug. $ sysctl vfs.zfs.arc_max vfs.zfs.arc_max: 268435456 $ sysctl kern.maxvnodes kern.maxvnodes: 179499 $ top last pid: 95789; load averages: 0.14, 0.16, 0.11=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 up 8+21:45:16 10:27:57 40 processes: 2 running, 38 sleeping CPU: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt, 100% idle Mem: 20M Active, 251M Inact, 2769M Wired, 2856M Free ARC: 456M Total, 87M MFU, 105M MRU, 1600K Anon, 8149K Header, 255M Other 40M Compressed, 154M Uncompressed, 3.87:1 Ratio Swap:=20 Lowering kern.maxvnodes below the default: $ sysctl kern.maxvnodes=3D10240 kern.maxvnodes: 179499 -> 10240 $ top last pid: 96130; load averages: 0.06, 0.12, 0.09=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 up 8+21:50:03 10:32:44 42 processes: 1 running, 41 sleeping CPU: 0.4% user, 0.0% nice, 0.4% system, 0.0% interrupt, 99.2% idle Mem: 21M Active, 233M Inact, 2773M Wired, 2868M Free ARC: 148M Total, 43M MFU, 29M MRU, 1600K Anon, 7678K Header, 66M Other 40M Compressed, 154M Uncompressed, 3.86:1 Ratio Swap: --=20 You are receiving this mail because: You are the assignee for the bug.=
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