Date: 21 Mar 2001 17:34:44 -0500 From: Randell Jesup <rjesup@wgate.com> To: Mike Smith <msmith@FreeBSD.ORG>, arch@FreeBSD.ORG Subject: Re: remind me again, why is MAXPHYS only 128k ? Message-ID: <ybusnk6oinv.fsf@jesup.eng.tvol.net.jesup.eng.tvol.net> In-Reply-To: Matt Dillon's message of "Wed, 21 Mar 2001 13:38:08 -0800 (PST)" References: <89046.985209441@critter> <200103212138.f2LLc8a21690@earth.backplane.com>
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Matt Dillon <dillon@earth.backplane.com> writes:
> When I last discussed MAXPHYS with people the issue that was predominant
> was the b_pages[] array embedded in the struct buf and the pages[] arrays
> declared in the VM paging code. I was worried that an increased MAXPHYS
> eating too much kernel stack and too much kernel memory. We also have
> the issue of the physical buffers (pbufs) reserving VM space permanently.
> If you increase MAXPHYS you quickly start to hit kernel VM limitations.
I seem to remember we thought that those could become pointers to
arrays instead of in-line; or at least optionally so. CHeck the archives
on freebsd.org for -arch; it wasn't that long ago.
--
Randell Jesup, Worldgate Communications, ex-Scala, ex-Amiga OS team ('88-94)
rjesup@wgate.com
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