Re: [PATCH] 2.5.15 IDE 61

Neil Conway
2002-05-15T11:46:36Z

Martin Dalecki wrote:
> The only problem is that having a shared lock between two queues apparently
> doesn't imply that the queues are behaving atomic on the request level
> among each others.

Correct - both queues can be active with I/O in flight at the same
time. But think about it: if this weren't the case, then the older
kernels (using global io_request_lock) would have had to serialize ALL
I/O, one request-queue active at a time, for every single
block-device...

> Apparenty the "sublimation" of the hwgroup and overall cleanup of
> data structures, just made many people awake and be aware of problems which
> where there already for a very very long time...

I'm not quite sure which problems you mean. The busy flag prevents any
clash. (But sure, if you change to per-device queues AND you ditch the
busy flag you're screwed.) Where is the problem?

cheers
Neil