CODEWITHSUNDEEP
linuxasynchronousiokey-value-storeaio
Mohammad Hedayati
Mohammad Hedayati

Reputation: 251

Applications using kernel AIO

Can anyone point me to some (preferably commonly-used) applications that use kernel AIO (i.e., io_submit() family), like any SQL/no-SQL database, etc.? I want it to be able to issue asynchronous reads with queue-depths of more than 1 on each thread to fully saturate a highly parallel SSD that supports 64> in-flight requests without noticeable degrade.

I am aware of InnoDB, but am looking for something simpler (possibly a KV store).

Update: I am not looking for sample codes, or synthetic benchmarks like fio+libaio. I am interested to find a set of applications that can saturate the device in a more realistic setting.

Upvotes: 4

Views: 683

Answers (1)

Mike Andrews
Mike Andrews

Reputation: 3206

One simple example of io_submit/io_getevents is in fio, a program that's an enormous help for testing and profiling block devices. It has a number of different I/O backends to support different OS's and different access techniques. The Linux AIO wrapper is in the author's repository on github: https://github.com/axboe/fio/blob/master/engines/libaio.c

The fio code is simple, but it's missing the eventfd integration, which you'll likely need. (I always have.) For this, the slightly more complicated, but straightforward code in QEMU's block layer provides a good example: https://github.com/qemu/qemu/blob/331ac65963ab74dd84659b748affa0b111486f06/block/linux-aio.c

You may find you can saturate your SSD from a single thread! Or, at least, it's worth testing. Fio can give you a good idea of what kind of throughput you can expect before you write the code. You can even configure it to do multiple threads.

Upvotes: 3

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