[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH][RFT] Make DMA timer driven
From: |
Edgar E. Iglesias |
Subject: |
Re: [Qemu-devel] [PATCH][RFT] Make DMA timer driven |
Date: |
Fri, 24 Oct 2008 11:22:43 +0200 |
User-agent: |
Mutt/1.5.16 (2007-06-09) |
On Fri, Oct 24, 2008 at 12:13:49AM +0100, Paul Brook wrote:
> > You can find info regarding CRIS/ETRAX testing here:
> > http://lists.gnu.org/archive/html/qemu-devel/2008-09/msg00279.html
> >
> > I tested the patch. It works but unfortunately DMA transfers to/from
> > the ethernet block now seem to emulate very slowly.
>
> Is there a reason you're deferring the DMA transfers, rather than completing
> them immediately? In most cases you want to do the DMA as soon as both ends
> are ready, and there's no benefit artificially delaying things. Any delay is
> entirely arbitrary, and won't work reliably.
Hello,
If you are refering to the etrax dma/ethernet, any delays are unintentional. I
removed the poll based ethernet receive path, so that rx packets now go
straight into the dma without waiting for DMA_run but unfortunately the timer
based DMA_run still slows things down for etrax.
I'll try to look at it more when I get a free time slot..
Thanks