Hi,
really a cool patch !
Also thanks for pointing out that glibc schedules only one I/O request at a
time. This seems to nullify all the possible benefits of using aio.
To avoid redundant work I want to post my current plans regarding I/O to the
list.
Right now I'm experimenting / building a performance test which should test
aio / threaded non-direct-io and direct-io performance because I/we think we
need more data to figure out how we could feed the linux kernel right for
different systems (Raid / non-raid) and to determine a promising I/O
strategy, then I hope we can add high level scheduling information / policies
to achieve better performance. Also we talked about the automatic adjustment
of trove I/O parameters...
I looked again at the bullopensource aio implementation, more specific the
blocking listio call. This seems to work for me without kernel patches (with
minor perf. penalities), also it seems to schedule all requests at once via
io_submit and does not delay other requests. Thus I think this might be nice
to test the kernel scheduler and check the behavior in case multiple requests
are available at once. I expect the I/O throughput to be better due to the
availability of more requests, this has to be verified, though. The listio
test runs X requests (I currently try 100) in one blocking listio request...
Hopefully I will soon get more data, once I complete the test I will finish
building the automatic diagram creation and release the testsuite in my
branch. One issue with the bull aio implemenation is that there is no use in
buffered I/O access, instead O_Direct is used in all cases and the data is
copied internally.
Comments are welcome,
Thanks,
julian
--
Liebe Grüße
Julian
---
Luke blows up his first TIE fighter.
Luke Skywalker:
Got 'im! I got 'im!
Han Solo:
Great, kid! Don't get cocky!
---
Why is the sea king of a hundred streams?
Because it lies below them.
Therefore it is the king of a hundred streams.
If the sage would guide the people, he must serve with humility.
If he would lead them, he must follow behind.
In this way when the sage rules, the people will not feel oppressed;
When he stands before them, they will not be harmed.
The whole world will support him and will not tire of him.
Because he does not compete,
He does not meet competition.
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