From owner-freebsd-net@FreeBSD.ORG Tue Feb 5 19:11:54 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 15D67341; Tue, 5 Feb 2013 19:11:54 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (bigknife-pt.tunnel.tserv9.chi1.ipv6.he.net [IPv6:2001:470:1f10:75::2]) by mx1.freebsd.org (Postfix) with ESMTP id E5EF7123; Tue, 5 Feb 2013 19:11:53 +0000 (UTC) Received: from pakbsde14.localnet (unknown [38.105.238.108]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 44833B91E; Tue, 5 Feb 2013 14:11:53 -0500 (EST) From: John Baldwin To: Randall Stewart Subject: Re: Driver patch to look at... Date: Tue, 5 Feb 2013 14:11:52 -0500 User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110714-p22; KDE/4.5.5; amd64; ; ) References: <990BD290-643B-4BC7-8D64-6D4CE987025A@lakerest.net> <00075DDD-73A1-4CA4-9574-036D43B071D9@lakerest.net> In-Reply-To: <00075DDD-73A1-4CA4-9574-036D43B071D9@lakerest.net> MIME-Version: 1.0 Content-Type: Text/Plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Message-Id: <201302051411.52495.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Tue, 05 Feb 2013 14:11:53 -0500 (EST) Cc: freebsd-net@freebsd.org, Robert Watson , Jack Vogel , Kip Macy X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Feb 2013 19:11:54 -0000 On Tuesday, February 05, 2013 2:08:15 pm Randall Stewart wrote: > Hmm >=20 > wait, I could probably do the compare to whats in the ring buffer ;-D I wouldn't bother. The compare and branch is probably more expensive than the store. > R > On Feb 5, 2013, at 2:04 PM, Randall Stewart wrote: >=20 > > Hmm > >=20 > > That would trade off a stack pointer + a compare > > vs always doing the move. > >=20 > > Thats fine until I have to add the _mc() version, then the put > > back would be an atomic, and most of the time the return from > > this is probably not changed=85 > >=20 > > I really would prefer not to since the compare and maybe store vs > > the always store.. though the same now, would be far more expensive > > in the _mc version.. if we do a _mc version of course ;-) > >=20 > > But I am willing to do whatever .. since this really needs to be fixed. > >=20 > > R > > On Feb 5, 2013, at 1:52 PM, John Baldwin wrote: > >=20 > >> On Tuesday, February 05, 2013 12:44:01 pm Randall Stewart wrote: > >>> Actually, no it is used. > >>>=20 > >>> If you look in if_var.h int he drbr_putback() function, it does > >>> a buf_ring_swap when the old mbuf pointer does not equal the > >>> new mbuf pointer. This *does* happen, I crashed at least once > >>> yesterday when the igb driver did something to free the original > >>> mbuf and return a new mbuf with the data (prepend or some such). > >>>=20 > >>> I also have found several issues that I have fixed this morning.. its= been > >>> crash city on my test beds.. > >>>=20 > >>> Here is the latest patch with all fixes and suggested changes from em= aste=20 > >> (thanks Ed) > >>=20 > >> Actually, one more suggestion then (since you have to keep putback). = It > >> would be nice to not have to require 'snext' in all the callers. How > >> about replace buf_ring_swap() with a buf_ring_putback_sc() that accept= s the > >> mbuf and just stores it at the head unconditionally and have drbr_putb= ack() > >> use that? > >>=20 > >> --=20 > >> John Baldwin > >> _______________________________________________ > >> freebsd-net@freebsd.org mailing list > >> http://lists.freebsd.org/mailman/listinfo/freebsd-net > >> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > >>=20 > >=20 > > ------------------------------ > > Randall Stewart > > 803-317-4952 (cell) > >=20 > > _______________________________________________ > > freebsd-net@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-net > > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > >=20 >=20 > ------------------------------ > Randall Stewart > 803-317-4952 (cell) >=20 >=20 =2D-=20 John Baldwin