Date: Mon, 18 Jun 2018 07:44:26 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 163461] [vfs] vfs.zfs.arc_max/vfs.zfs.arc_meta_limit defaults aren't wise Message-ID: <bug-163461-227-b4yFGazPDc@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-163461-227@https.bugs.freebsd.org/bugzilla/> References: <bug-163461-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D163461 Shane <FreeBSD@ShaneWare.Biz> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |FreeBSD@ShaneWare.Biz --- Comment #3 from Shane <FreeBSD@ShaneWare.Biz> --- Rather than start a new report I will jump into this old one. Currently arc_max is set to the larger of (5/8 of kmem_size) or (kmem_size minus 1G) - for a system with 8G of ram 5/8 is 5G with kmem size minus 1G a= bout 6GB While that sounds ok, we also have max_wired which seems to default to 5G (I see that on an 8G and 16G setup) the issue results from arc being wired but= not included in the max_wired count, that means an 8G system allows 10G to get wired! a 16GB system allows 20GB to be wired! When a system has more than 70% of physical ram wired, it gets exteremely s= low and over 80% wired gives a very high chance of needing a hard reset. At the minimum we need to consider max_wired in the arc_max calculation. I do believe the arc_max default should be even smaller to be better suited= to more common setups that run processes that use ram, a sysadmin starting a f= ile server that wants to use most of the ram for cache should know how to set t= his as desired, the other 80-90% of users shouldn't have to adjust a setting th= at is suited to the smaller use case. --=20 You are receiving this mail because: You are the assignee for the bug.=
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