Messages in this thread |  | | From | Daniel Phillips <> | Subject | Re: Calculating kernel logical address .. | Date | Mon, 9 Sep 2002 20:50:38 +0200 |
| |
On Monday 09 September 2002 20:43, Richard B. Johnson wrote: > On Mon, 9 Sep 2002, Daniel Phillips wrote: > > > On Monday 09 September 2002 20:00, Richard B. Johnson wrote: > > > For some reason, (claimed performance reasons) user-mode code > > > has to be able to get data directly from hardware with no > > > intervening copy operation. I think any claimed advantage goes > > > away when you look at the overhead necessary for user-mode > > > code to sleep before, and awaken after, the DMA operation but > > > often marketing departments make those decisions. > > > > Pfft. Try turning off ide dma and see what happens. > > I know that DMA works, I'm talking about DMA direct-to-user > which is not what the file-systems that use DMA do.
The next generation of fast, parallel filesystems relies on dma to/from user space. Besides, what do you think happens when you read/write a mmap?
-- Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |