Messages in this thread |  | | Subject | Re: linux-2.4.10-pre5 | Date | Mon, 10 Sep 2001 00:54:26 +0100 (BST) | From | Alan Cox <> |
| |
How do you plan to handle the situation where we have multiple instances of the same 4K disk block each of which contains 1K of data in the start of the page copy and 3K of zeroes.
This isnt idle speculation - thing about BSD UFS fragments.
> anyway, I very much doubt it has any good properties to make software more > complex by having that kind of readahead in sw.
Even the complex stuff like the i2o raid controllers seems to benefit primarily from file level not physical readahead, that gives it enough to do intelligent scheduling and to keep the drive firmware busy making good decisions (hopefully)
Even with software raid the physical readahead decisions belong in the raid code as they are tied to strip alignment and sizes not high level policy
Alan - 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/
|  |