Re: [PATCH 1/2] cfq-iosched: remove dead_key from cfq_io_context

From: Konstantin Khlebnikov
Date: Fri May 21 2010 - 10:54:05 EST

On 21.05.2010 13:40, Jens Axboe wrote:
On Thu, May 20 2010, Konstantin Khlebnikov wrote:
Remove ->dead_key field from cfq_io_context to shrink its size to 128 bytes.
(64 bytes for 32-bit hosts)

Use lower bit in ->key as dead-mark, instead of moving key to separate field.
After this for dead cfq_io_context we got cic->key != cfqd automatically.
Thus, io_context's last-hit cache should work without changing.

Now to check ->key for non-dead state compare it with cfqd,
instead of checking ->key for non-null value as it was before.

Plus remove obsolete race protection in cfq_cic_lookup.
This race gone after v2.6.24-1728-g4ac845a

This, and the second patch, look really good. How much testing have you
done with it?

I have run multiple fsstress and simultaneously switch io-scheduler in loop
for several hours, no oopses and leaks detected.
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