Date: Sun, 21 Feb 1999 09:47:16 +0000 (GMT) From: Doug Rabson <dfr@nlsystems.com> To: Terry Lambert <tlambert@primenet.com> Cc: dillon@apollo.backplane.com, freebsd-hackers@FreeBSD.ORG Subject: Re: Panic in FFS/4.0 as of yesterday Message-ID: <Pine.BSF.4.05.9902210943270.82049-100000@herring.nlsystems.com> In-Reply-To: <199902210011.RAA22231@usr08.primenet.com>
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On Sun, 21 Feb 1999, Terry Lambert wrote: > > I think promoting directory writes (and directory reads probably) might be > > the simplest solution. > > Hum. This is trivial... > > Let's see... is there a free flag? Yes... > > OK, here's code to add the ability to expedite placement of async > writes. It' doesn't insert them in order behind other expedited > writes, so it turns the expedited stuff LIFO. This is probably > suboptimal, but can't happen in dependent operations, so what the > heck... > > When you use the code, be sure to *not* set the flag if soft updates > are in effect (I think that's a caller issue, not a callee issue, since > it would complicate the bdwrite code, probably unacceptably. I don't think this will do the job at all. The buffers in question are not delayed writes, so all this patch will do is change the order of the LOCKED and LRU lists, probably pessimising the reuse of those buffers. I think the flag needs to be implemented in the driver. The driver should check for the EXPEDITE flag and either maintain two queues for the two possible priorities or place the buffer at the front of a single work queue. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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