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Subject: Re: [PATCH] block: BFQ default for single queue devices
From: Bart Van Assche <bvanassche@acm.org>
To: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
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On Thu, 2018-10-04 at 20:25 +-0100, Alan Cox wrote:
+AD4 +AD4 I agree with Jens that it's best to leave it to the Linux distributors to
+AD4 +AD4 select a default I/O scheduler.
+AD4 
+AD4 That assumes such a thing exists. The kernel knows what devices it is
+AD4 dealing with. The kernel 'default' ought to be 'whatever is usually best
+AD4 for this device'. A distro cannot just pick a correct single default
+AD4 because NVME and USB sticks are both normal and rather different in needs.

Which I/O scheduler works best also depends which workload the user will run.
BFQ has significant advantages for interactive workloads like video replay
with concurrent background I/O but probably slows down kernel builds. That's
why I'm not sure whether the kernel should select the default I/O scheduler.

Bart.