From owner-freebsd-current Mon Feb 11 17:44:51 2002 Delivered-To: freebsd-current@freebsd.org Received: from mail12.speakeasy.net (mail12.speakeasy.net [216.254.0.212]) by hub.freebsd.org (Postfix) with ESMTP id 3070E37B405 for ; Mon, 11 Feb 2002 17:44:48 -0800 (PST) Received: (qmail 5623 invoked from network); 12 Feb 2002 01:44:47 -0000 Received: from unknown (HELO laptop.baldwin.cx) ([65.91.174.125]) (envelope-sender ) by mail12.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 12 Feb 2002 01:44:47 -0000 Message-ID: X-Mailer: XFMail 1.4.0 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: Date: Mon, 11 Feb 2002 20:44:07 -0500 (EST) From: John Baldwin To: Julian Elischer Subject: Re: ucred holding patch, BDE version Cc: current@freebsd.org, bde@freebsd.org, Alfred Perlstein Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On 12-Feb-02 Julian Elischer wrote: > The proclock is needed to get the reference, > guarding against other threads, and giant is needed fo rnot to free it > because if it reaches a refcount of 0 it needs to call free(). (which john > assures me needs Giant at this time). > We could avoid the proclock with judicious use of an atomic refcount > incrementing method. _No_! The proc lock is protecting p_ucred, it can't go away! What _can_ go away is the per-ucred mutex to protect the refcount if we ever revive the refcount API. > When Giant goes away it won't be so bad but it will STILL be quicker to > not drop it across userland. Yes. Actually, calling free() can still be rather expensive even when Giant is gone. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message