Subject: Re: FreeBSD Bus DMA
To: Justin T. Gibbs <>
From: Perry E. Metzger <>
List: tech-kern
Date: 06/12/1998 00:54:22
"Justin T. Gibbs" writes:
> I believe I have made a compelling case, along with real world numbers
> comparing the NetBSD and FreeBSD implementations, for why allowing
> deferred allocations is a win.

What numbers? you've never given a single benchmark.

> I have also given concreate numbers showing the space savings
> possible for implementations that don't need to keep dm_segs like
> data in the bus_dmamap_t object.

No you haven't. You didn't give a single number. Jason gave a number,
though -- he showed how this might save as much as 5000 bytes in total
on my machine, worst case. You will pardon me for being less than

> You can also infer that a system that uses substantially less memory
> for bus dma glue (on the order of MBs of data) will achieve better
> performance simply from having additional free pages to apply to
> other applications.

I'd say I can live without the extra free *page* (singular).