From owner-freebsd-hackers Fri Nov 27 15:41:24 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id PAA08350 for freebsd-hackers-outgoing; Fri, 27 Nov 1998 15:41:24 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from smtp04.primenet.com (smtp04.primenet.com [206.165.6.134]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id PAA08342 for ; Fri, 27 Nov 1998 15:41:23 -0800 (PST) (envelope-from tlambert@usr02.primenet.com) Received: (from daemon@localhost) by smtp04.primenet.com (8.8.8/8.8.8) id QAA08064; Fri, 27 Nov 1998 16:41:16 -0700 (MST) Received: from usr02.primenet.com(206.165.6.202) via SMTP by smtp04.primenet.com, id smtpd008053; Fri Nov 27 16:41:13 1998 Received: (from tlambert@localhost) by usr02.primenet.com (8.8.5/8.8.5) id QAA24991; Fri, 27 Nov 1998 16:41:09 -0700 (MST) From: Terry Lambert Message-Id: <199811272341.QAA24991@usr02.primenet.com> Subject: Re: SYSV Semaphores & mmap problems To: dillon@apollo.backplane.com (Matthew Dillon) Date: Fri, 27 Nov 1998 23:41:09 +0000 (GMT) Cc: tlambert@primenet.com, joelh@gnu.org, DBECK@ludens.elte.hu, freebsd-hackers@FreeBSD.ORG In-Reply-To: <199811240147.RAA11543@apollo.backplane.com> from "Matthew Dillon" at Nov 23, 98 05:47:24 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > The difference between mmap() and SysV shared memory isn't so bad. The > mmap()'d file will basically get synced every 30 seconds or so by the > syncer daemon. madvise() can be used to pre-fault any pages already in > the cache. > > I think all that is needed is a way to flag a file so the syncer doesn't > touch it under normal circumstances, instead allowing its pages to be > synced by normal paging activity. You can then madvise(... MADV_FREE) > the pages after you are through with the shared memory segment to throw > them away. The question to ask is "Why did Oracle pay John Dyson to make FreeBSD's SYSV SHM faster, and reject mmap(), even though the Oriacle source code supports using mmap()?". Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message