Subject: Re: 1.6.2 kernel: ex driver sometimes can't allocate
To: Chapman Flack <>
From: Jachym Holecek <>
List: tech-kern
Date: 09/21/2004 23:35:13

> > A compromise might be the following: when certain memory pages are
> > required but dirty, some *other* pages that are clean can be discarded,
> > and the dirty pages shuffled around so that they now occupy their
> > physical memory.
> I like it - it's certainly a lot faster than kicking them to disk; now
> is it fast enough to do within bus_dma_alloc( ...NOWAIT) ?  what are the
> latency requirements there?

As bus_dma_alloc(...NOWAIT) can be used from an intr handler, another
flag allowing this "extra effort" could be appropriate, so that device
driver writers can disable it on latency-critical paths?

	-- Jachym Holecek