On Thursday March 21, camhanaich99@yahoo.com wrote:
> Hello!
>
> I've noticed that RAID5 needs porting from BH's to BIO's. Where would one
> start if interested in doing this. I notice that one would need to change the
> arrays of BH's in the raid5 struct in raid5.h, as well as renaming several
> other variables which currently have md_ prepended to the beginning. This
> leaves all the BH handling code in raid5.c. Does this require algorithm
> changes, or is it basically replace bh code for simmilar code using bio's?
I think there is a fundamental issue that raid5 want to deal in 4k
sized requests and bios can be much bigger than this. So there needs
to be a clean mechanism to dice up a bio into little bits (without
blocking on memory allocation at the wrong time) and to give them to
raid5. A similar dicing up is needed for raid0, which would want chunk
sized bits, and linear, which would sometimes want to cut a bio in
half and some particular point.
It's on my list of things to worry about but I just haven't had a
chance yet.
NeilBrown
-
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/
This archive was generated by hypermail 2b29 : Sat Mar 23 2002 - 22:00:26 EST