Re: Huge performance issue with cciss driver on HP DL385 servers(2.6.13 -> 2.6.17)

[Xavier Roche]

Erik Mouw a écrit :
> AFAIK buffers for direct IO need to be *page* aligned. Use something
> like:
> I guess you got away with it cause your 512 byte alignment happened to
> align on a page, but you shouldn't count on that. However...

This example was actually just a minimal example - the running test is
correctly aligned.

> You should check the return value of pwrite().

Also checked in the "real" stress program.

Note that this problem is hard to reproduce, and might be related to
very strange I/O (and/or DMA access) operation ordering. The fact that
the program must be run just after a reboot (or the problem is not
easily reproductible) is something really fishy.
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