Date: Wed, 10 Jun 2009 09:23:41 -0400 From: John Baldwin <jhb@freebsd.org> To: Dag-Erling =?utf-8?q?Sm=C3=B8rgrav?= <des@des.no> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Kip Macy <kmacy@freebsd.org>, Dmitry Morozovsky <marck@rinet.ru> Subject: Re: svn commit: r193878 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <200906100923.42093.jhb@freebsd.org> In-Reply-To: <86ljo0wgnv.fsf@ds4.des.no> References: <200906100121.n5A1LWVO089719@svn.freebsd.org> <3c1674c90906100008i4c632312j32f223b8aca14934@mail.gmail.com> <86ljo0wgnv.fsf@ds4.des.no>
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On Wednesday 10 June 2009 6:02:12 am Dag-Erling Sm=C3=B8rgrav wrote: > Kip Macy <kmacy@freebsd.org> writes: > > Dmitry Morozovsky <marck@rinet.ru> writes: > > > Hmm, I failed to see how boolean prevent the usage: > > > > > > if arch=3D=3Di386 || memsize < 4G > > > =C2=A0 =C2=A0 =C2=A0 =C2=A0zfs_prefetch=3D0 > > > else > > > =C2=A0 =C2=A0 =C2=A0 =C2=A0zfs_prefetch=3D1 > > > > > > and admin can flip the switch to non-default position. > > > > > Right, what you're advocating is zfs_prefetch_non_default. Which is > > simpler, but still rather weird. >=20 > No, he's advocating zfs_prefetch_enable which is initialized to either 0 > or 1 at boot time and can be administratively set to either 0 and 1 > regardless of its initial value. I don't see the problem... Yes, you can simply do a TUNABLE_INT_FETCH() after the initial calculation = to=20 honor any user override. Many existing settings already work this way wher= e=20 the user can override the auto-tuned value (e.g. all the buffer-cache tunin= g=20 settings). =2D-=20 John Baldwin
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