From owner-freebsd-arch Sun Jul 14 3:20:19 2002 Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 67BF937B400 for ; Sun, 14 Jul 2002 03:20:17 -0700 (PDT) Received: from gw.catspoiler.org (217-ip-163.nccn.net [209.79.217.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 09AB743E67 for ; Sun, 14 Jul 2002 03:20:14 -0700 (PDT) (envelope-from dl-freebsd@catspoiler.org) Received: from mousie.catspoiler.org (mousie.catspoiler.org [192.168.101.2]) by gw.catspoiler.org (8.12.5/8.12.5) with ESMTP id g6EAK4wr020922; Sun, 14 Jul 2002 03:20:08 -0700 (PDT) (envelope-from dl-freebsd@catspoiler.org) Message-Id: <200207141020.g6EAK4wr020922@gw.catspoiler.org> Date: Sun, 14 Jul 2002 03:20:04 -0700 (PDT) From: Don Lewis Subject: Re: wiring the sysctl output buffer To: phk@critter.freebsd.dk Cc: arch@FreeBSD.ORG In-Reply-To: <56792.1026640649@critter.freebsd.dk> MIME-Version: 1.0 Content-Type: TEXT/plain; charset=us-ascii Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message