From owner-freebsd-hackers Thu Dec 24 09:21:18 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id JAA24605 for freebsd-hackers-outgoing; Thu, 24 Dec 1998 09:21:18 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from apollo.backplane.com (apollo.backplane.com [209.157.86.2]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id JAA24600 for ; Thu, 24 Dec 1998 09:21:16 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.1/8.9.1) id JAA27982; Thu, 24 Dec 1998 09:21:01 -0800 (PST) (envelope-from dillon) Date: Thu, 24 Dec 1998 09:21:01 -0800 (PST) From: Matthew Dillon Message-Id: <199812241721.JAA27982@apollo.backplane.com> To: "John S. Dyson" Cc: hackers@FreeBSD.ORG Subject: Re: M_KERNEL in sys/malloc.h ??? Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Matthew Dillon said: :> Does anyone know what M_KERNEL is sys/malloc.h is supposed to do? It :> is used in precisely two places in the code as far as I can tell: :> :> vm/default_pager.c: if (swap_pager_swp_alloc(object, M_KERNEL) != 0) { :> vm/default_pager.c: if (swap_pager_swp_alloc(object, M_KERNEL) != 0) { :> vm/swap_pager.c: spc->spc_bp = malloc(sizeof(*bp), M_TEMP, M_KERNEL); :> :> But kern/kern_malloc.c doesn't appear to really use it. On the otherhand :> I do see lots of absolute comparison of the malloc 'flags' to M_WAITOK :> (0) or M_NOWAIT which the use of M_KERNEL would interfere with. I can't :> tell if the side effects are something that are expected, or if the :> side effects are a bug. :> :> Anybody know? :> :As I remember, M_KERNEL means that it really needs memory. waiting :for memory is bad, and dip deeply into the page reserves. Normally, the :malloc (in vm_kern) code will only dip into the interrupt accessible :free pages. The M_KERNEL allows it to dip into all of the pages. Ok, I'll document it then and make sure it operates the same with my cleanups. -Matt :John | Never try to teach a pig to sing, :dyson@iquest.net | it makes one look stupid Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet Communications & God knows what else. (Please include original email in any response) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message