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I/O scheduler performanceI/O scheduler performancePosted Aug 23, 2010 20:04 UTC (Mon) by axboe (subscriber, #904)In reply to: I/O scheduler performance by dlang Parent article: A systemd status update
A scheduler like CFQ will attempt to provide a mix of what you describe, depending on how you submit it. If the submission is done from one process, it will assume that you want it to be done as fast as possible. It'll be sorted accordingly. If done from multiple processes or threads, it will attempt to provide equal progress while preserving overall throughput.
What you describe is true on classical work conserving IO schedulers, it's not the case for the default Linux IO scheduler.
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I/O scheduler performance Posted Sep 8, 2010 11:15 UTC (Wed) by epa (subscriber, #39769) [Link]
So, then, the way to get fast I/O is to make asynchronous I/O calls from a single thread (so that the scheduler knows that fairness doesn't matter) rather than spawning multiple threads or processes.
Is there any way to fork subprocesses but still let CFQ know that they're all related and happy to altruistically share I/O bandwidth between them, so it doesn't try to slice up I/O requests fairly at the expense of total throughput?
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