[PC-BSD Dev] vm.pmap.pg_ps_enabled sysctl tunable

N V VaNs9 at yandex.ru
Thu Aug 5 07:14:06 PDT 2010


There is sysctl vm.pmap.pg_ps_enabled tunable available, controlling: "application memory pages are dynamically promoted to or demoted from superpages" . It has been introduced in 7.2. It is off by default.
Official info here: http://www.freebsd.org/releases/7.2R/relnotes.html
Dev.team: http://lists.freebsd.org/pipermail/freebsd-current/2008-August/087605.html
So, I haven't found any final info, advising where to enable it, and where to not. A mean systems, which are advised to use this variable, and which are not. There is only a "50-50" about k8-equipped systems.
I use systems equipped with Pentium D 2.80GHz, Core 2 Duo E4500 and AMD Turion 64 TL-60. The vm.pmap.pg_ps_enabled is turned on. I have no problem with it. Used both i386/amd64 FreeBSD >=7.2 on them, except Pentium D system (there is i386). But, I haven't done any performance tests.
Since PC-BSD i386 may be used on some old systems, may be it'll be useful to turned it on in amd64 version?


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