Messages in this thread | | | From | "Stephen C. Tweedie" <> | Date | Tue, 1 Jun 1999 00:38:32 +0100 (BST) | Subject | Re: XFS and journalling filesystems |
| |
Hi,
On Sat, 29 May 1999 10:44:55 -0700 (PDT), Tim Smith <tzs@tzs.net> said:
> On Thu, 27 May 1999, Theodore Y. Ts'o wrote: >> DMA in and out of memory, I was appropriately horrified. I'm glad to >> hear it wasn't true, and that you had no part in implementing or >> designing such a horrible hack (i.e., direct device-to-device I/O). :-)
> Is direct device-to-device I/O always bad?
Not exactly, but often. It complicates things like error recovery enormously, and it rapidly becomes useless as soon as you have devices on multiple buses (although SANs such fibrechannel fabrics do help there). As long as you have spare bus bandwidth, doing zero-copy transfer through the OS is as fast, and it is much cleaner.
--Stephen
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |