Messages in this thread | | | From | "Adam J. Richter" <> | Date | Sat, 15 Jun 2002 02:10:53 -0700 | Subject | Re: bio_chain: proposed solution for bio_alloc failure and large IO simplification |
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>> So, I need a fourth location at in generic_make_request >> just before the call to q->make_request_fn, like so: >> >> if (q->make_request_fn != __make_request) { >> int flags; >> spin_lock_irqsave(q->lock, flags); >> clear_hint(bio); >> spin_unlock_irqrestore(q->lock, flags); >> } >> ret = q->make_request_fn(q, bio);
>Irk, this is ugly. But how you are moving away from the initial goal (or >maybe this was your goal the whole time, just a single merge hint?) of >passing back the hint instead of maintaing it in the queue. So let me >ask, are you aware of the last_merge I/O scheduler hint? Which does >exactly this already...
The code that I think I more or less have in my head has not changed (aside from that fourth test).
Although I was not aware of q->last_merge, I see that it is not what I want. I want up to one hint per request, for the last bio in the request. bi_hint would be null for all bio's except possibly the last bio in a request. I do not want just one hint per queue.
If it is unclear what I mean, perhaps I really need to code it up to explain it. and we can discuss it from there.
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