Date: Sun, 14 Jul 2002 12:27:50 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Don Lewis <dl-freebsd@catspoiler.org> Cc: arch@FreeBSD.ORG Subject: Re: wiring the sysctl output buffer Message-ID: <62432.1026642470@critter.freebsd.dk> In-Reply-To: Your message of "Sun, 14 Jul 2002 03:20:04 PDT." <200207141020.g6EAK4wr020922@gw.catspoiler.org>
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In message <200207141020.g6EAK4wr020922@gw.catspoiler.org>, Don Lewis writes: >On 14 Jul, Poul-Henning Kamp wrote: >> In message <200207140954.g6E9sBwr020599@gw.catspoiler.org>, Don Lewis writes: >>>On 14 Jul, Poul-Henning Kamp wrote: > >>>> It used to be that sysctl unconditionally wired the output buffer, >>>> but that gave rise to a host of other problems. >>> >>>Anything specific that I should be aware of? >> >> No, just bad deadlocks and such. >> >> 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"). -- 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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