From owner-freebsd-chat Mon Dec 7 02:12:29 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id CAA10651 for freebsd-chat-outgoing; Mon, 7 Dec 1998 02:12:29 -0800 (PST) (envelope-from owner-freebsd-chat@FreeBSD.ORG) Received: from gilgamesch.bik-gmbh.de (gilgamesch.bik-gmbh.de [194.233.237.91]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA10646 for ; Mon, 7 Dec 1998 02:12:26 -0800 (PST) (envelope-from cracauer@gilgamesch.bik-gmbh.de) Received: (from cracauer@localhost) by gilgamesch.bik-gmbh.de (8.8.8/8.7.3) id LAA20342; Mon, 7 Dec 1998 11:12:07 +0100 (MET) Message-ID: <19981207111206.A20322@cons.org> Date: Mon, 7 Dec 1998 11:12:06 +0100 From: Martin Cracauer To: Brett Glass , chat@FreeBSD.ORG Subject: Re: Question regarding Linux emulation References: <4.1.19981206215315.042becc0@127.0.0.1> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93.1i In-Reply-To: <4.1.19981206215315.042becc0@127.0.0.1>; from Brett Glass on Sun, Dec 06, 1998 at 09:53:49PM -0700 Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org In <4.1.19981206215315.042becc0@127.0.0.1>, Brett Glass wrote: > I was asked these questions this evening, and don't know the answers. > > How much of a speed penalty, if any, is incurred for using Linux emulation > under FreeBSD compared to running a natively compiled version of the same > program (or, for that matter, running the Linux program under Linux)? How > "thin" is the Linux emulation layer? What calls can be expected to incur a > substantial penalty due to translation of data structures, emulation of > system facilities, etc.? The emulation is mostly just an additional function call and a very short code path to map some table to another (unually the same :-) or to rebuild function arguments, often structs. Even signal delivery code is quite small. Remember that this is only done for system calls and a minimal system call - emulated or not - is so costly in itself that this little extra CPU stuff is unnoticeable. Martin -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Martin Cracauer http://www.cons.org/cracauer BSD User Group Hamburg, Germany http://www.bsdhh.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message