Date: Sun, 14 Jul 2002 03:45:57 -0700 (PDT) From: Don Lewis <dl-freebsd@catspoiler.org> To: phk@critter.freebsd.dk Cc: arch@FreeBSD.ORG Subject: Re: wiring the sysctl output buffer Message-ID: <200207141046.g6EAjvwr020972@gw.catspoiler.org> In-Reply-To: <62432.1026642470@critter.freebsd.dk>
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On 14 Jul, Poul-Henning Kamp wrote: > In message <200207141020.g6EAK4wr020922@gw.catspoiler.org>, Don Lewis writes: >>On 14 Jul, Poul-Henning Kamp wrote: >>> You may also want to restrict the amount of buffer you pin >>> if I hand the kernel a 2G buffer for a 4 byte sysctl integer >>> you wouldn't want to pin it all. >> >>Yeah, that could be bad, but the SYSCTL_OUT() in the current API pins >>the whole user supplied buffer on the first call. My new entry point >>does the same thing, but allows the caller to do this potentially >>blocking operation earlier. > > I know, but that also affords an opportunity to be smarter (ie: letting > the entry point say "I need this much storage"). I like this idea, though we'd want to move the new interface to the recommended list. There is also the problem keeping track of how much memory we wired. The current sysctl exit code unwires the entire user supplied buffer. If we only wire a portion, then we would need to add a member to the sysctl_req structure to record how much was wired so that we could unwire that amount on exit. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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