Date: Mon, 13 Aug 2018 10:35:38 -0700 From: Mark Millard <marklmi@yahoo.com> To: bob prohaska <fbsd@www.zefox.net> Cc: Mark Johnston <markj@FreeBSD.org>, John Kennedy <warlock@phouka.net>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: RPI3 swap experiments ["was killed: out of swap space" with: "v_free_count: 5439, v_inactive_count: 1"] Message-ID: <FC0798A1-C805-4096-9EB1-15E3F854F729@yahoo.com> In-Reply-To: <0D8B9A29-DD95-4FA3-8F7D-4B85A3BB54D7@yahoo.com> References: <EC74A5A6-0DF4-48EB-88DA-543FD70FEA07@yahoo.com> <20180806155837.GA6277@raichu> <20180808153800.GF26133@www.zefox.net> <20180808204841.GA19379@raichu> <2DC1A479-92A0-48E6-9245-3FF5CFD89DEF@yahoo.com> <20180809033735.GJ30738@phouka1.phouka.net> <20180809175802.GA32974@www.zefox.net> <20180812173248.GA81324@phouka1.phouka.net> <20180812224021.GA46372@www.zefox.net> <B81E53A9-459E-4489-883B-24175B87D049@yahoo.com> <20180813021226.GA46750@www.zefox.net> <0D8B9A29-DD95-4FA3-8F7D-4B85A3BB54D7@yahoo.com>
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On 2018-Aug-12, at 8:36 PM, Mark Millard <marklmi at yahoo.com> wrote: > On 2018-Aug-12, at 7:12 PM, bob prohaska <fbsd at www.zefox.net> = wrote: >=20 >> . . . >> Would 1024 be enough to turn OOMA off completely? That's what I = originally wanted to=20 >> try. >=20 [The 1024 is for vm.pageout_oom_seq.] I'm going to try a different wording about vm.pageout_oom_seq to address such questions: vm.pageout_oom_seq indirectly sets how long FreeBSD will tolerate Low Free RAM (by its Low Free RAM criteria). The "indirect" is because my wording is time based but the vm.pageout_oom_seq units are not. For a given environment smaller vs. larger is less time vs. more time. So, while one can make FreeBSD tolerate Low Free RAM longer (up to a point, apparently huge), no specific value directly turns off OOM (better: Low Free RAM) process killing. (Based on mathematical arithmetic. I've not analyze odd consequences of causing overflows for the code's details.) The approximation to turning off being intolerant of Low Free RAM is to have vm.pageout_oom_seq so large that you would not be willing to wait for the process kills to start. But the minimum for that is likely not obvious, so just use a fairly large figure for the int value for the architecture being tested. (rpi2 V1.1's and rpi3's have fairly large int types in C.) (I've assumed that the representation of vm.pageout_oom_seq is respected everywhere that it is used. If someplace mixes it with smaller types, this would need to be considered for what is "fairly large". This would require a code inspection.) =3D=3D=3D Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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