Date: Mon, 12 Jul 1999 10:38:45 -0700 From: John-Mark Gurney <gurney_j@efn.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Luoqi Chen <luoqi@watermarkgroup.com>, dfr@nlsystems.com, jeremyp@gsmx07.alcatel.com.au, freebsd-current@FreeBSD.ORG, mike@ducky.net Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") Message-ID: <19990712103845.39296@hydrogen.fircrest.net> In-Reply-To: <199907121647.JAA70249@apollo.backplane.com>; from Matthew Dillon on Mon, Jul 12, 1999 at 09:47:11AM -0700 References: <199907121032.GAA14268@lor.watermarkgroup.com> <199907121647.JAA70249@apollo.backplane.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Matthew Dillon scribbled this message on Jul 12: > p.s. I'm pretty sure that the lock prefix costs nothing on a UP system, > and probably wouldn't be noticed on an SMP system either because the > write-allocation overhead is already pretty bad. But I haven't tested > it. actually, I'm not so sure, it guarantees that NO other bus operation will succeed while this is happening... what happens if a pci bus mastering card makes a modification to this value? sure, it normally won't happen, but it can... and w/o the lock prefix, this CAN happen from what I understand of the architecture... so, it does have to lock even the memory bus, simply the cache isn't enough for the lock to do what it needs... -- John-Mark Gurney Voice: +1 541 684 8449 Cu Networking P.O. Box 5693, 97405 "The soul contains in itself the event that shall presently befall it. The event is only the actualizing of its thought." -- Ralph Waldo Emerson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19990712103845.39296>