Date: Thu, 23 Jan 2014 14:30:46 -0500 From: John Baldwin <jhb@freebsd.org> To: Adrian Chadd <adrian.chadd@gmail.com> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, Rui Paulo <rpaulo@freebsd.org>, Neel Natu <neel@freebsd.org> Subject: Re: svn commit: r260898 - head/sys/kern Message-ID: <201401231430.46532.jhb@freebsd.org> In-Reply-To: <CAJ-Vmok0J9cbjEzsNDD1nVx22rssp34oSE6H7aomMyYkwbSRZg@mail.gmail.com> References: <201401200159.s0K1xa5X012123@svn.freebsd.org> <0F26E4E1-5D75-413E-B92B-AA7092B87D89@FreeBSD.org> <CAJ-Vmok0J9cbjEzsNDD1nVx22rssp34oSE6H7aomMyYkwbSRZg@mail.gmail.com>
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On Thursday, January 23, 2014 2:35:54 am Adrian Chadd wrote: > On 22 January 2014 20:34, Rui Paulo <rpaulo@freebsd.org> wrote: > > On 22 Jan 2014, at 20:05, Adrian Chadd <adrian.chadd@gmail.com> wrote: > > > >> .. Make it be an offset into the table rather than a pointer, then we can do dirty rcu style hacks to just replace and grow the table as we need more memory. > >> > >> Don't we have a standard way to pull memory from the top of the physmem area early on for allocations like this? > > > > Perhaps a bit overkill for this problem? > > We already have platform dependent ways of doing this in the VM init > path for exactly this - structures needed early at boot. > > It may be overkill but it may also be the cleanest way to allow > boot-time tuned things based on early available information, which we > may want to do when it's time to boot a single kernel on a 2-core atom > board or a 256 core intel/amd server board. The number of witness structures (WITNESS_COUNT) should not vary in those cases. -- John Baldwin
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