Date: Tue, 20 Sep 2005 22:33:43 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, ru@FreeBSD.org, cvs-all@FreeBSD.org, "M. Warner Losh" <imp@bsdimp.com> Subject: Re: cvs commit: src/sys/dev/an if_an.c src/sys/dev/arl if_arl_isa.c src/sys/dev/awi if_awi_pccard.c src/sys/dev/cm if_cm_isa.c src/sys/dev/cnw if_cnw.c src/sys/dev/cp if_cp.c src/sys/dev/cs if_cs.c src/sys/dev/ed if_ed.c src/sys/dev/em if_em.c ... Message-ID: <20050920223315.V34322@fledge.watson.org> In-Reply-To: <20050920222930.N34322@fledge.watson.org> References: <200509190310.j8J3ALgt095979@repoman.freebsd.org> <20050919055028.GC65954@ip.net.ua> <20050919.083146.105425670.imp@bsdimp.com> <200509201551.11396.jhb@FreeBSD.org> <20050920222930.N34322@fledge.watson.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 20 Sep 2005, Robert Watson wrote: > > On Tue, 20 Sep 2005, John Baldwin wrote: > >> Regarding other comments I saw today on some e-mail or another, I do think >> that to make the locking sane, we might should push the checks for >> IFF_DRV_RUNNING down into the foo_start() routines rather than doing it in >> the network layer where the driver lock isn't held. > > This was a change I was thinking of trying to get into 6.0 a few weeks > ago, but was worried that wholesale frobbing of the network interface > drivers would introduce too many bugs. Also, it will increase the cost > of injecting packets into the send queue under load as you'll always > have to acquire and drop the driver mutex to test the flag. I.e., it's > not clear we're actually racing, but we might pay a hefty cost for > fixing it. If you want to take a cut at it, I'm happy to help > characterize the cost and decide if it's the right thing to do. It > would be nice to get it into 6.0 if possible as it will become part of > the device driver API if so. ... getting late ... I mean the IFF_DRV_OACTIVE flag test used in the handoff. Robert N M Watson
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20050920223315.V34322>