Date: Wed, 21 Mar 2001 22:51:44 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Matt Dillon <dillon@earth.backplane.com> Cc: mjacob@feral.com, arch@FreeBSD.ORG Subject: Re: remind me again, why is MAXPHYS only 128k ? Message-ID: <89687.985211504@critter> In-Reply-To: Your message of "Wed, 21 Mar 2001 13:42:01 PST." <200103212142.f2LLg1921851@earth.backplane.com>
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In message <200103212142.f2LLg1921851@earth.backplane.com>, Matt Dillon writes: >:Yeah, it's a mistake for struct buf/bio to use a fixed array of pages >:(b->b_pages) If we made that a ** instead we could have a variable >:MAXPHYS... >: >:-- >:Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >:phk@FreeBSD.ORG | TCP/IP since RFC 956 > > Remember that allocating struct buf's cannot block in MALLOC or anything > like that. It is difficult to deal with struct buf exhaustion in > vfs/bio. We can't add any new blocking conditions anywhere and still > have a stable system. Well, physio can wait, and that is the sticky point for tapes and such. For normal bufs the field would be allocated at boot to point to the usual sized array. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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