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Re: [Xen-devel] [PATCH] make blkfront/blktagp2 respect the elevator=xyz command line option

For blkfront, I agree. Is there a use case for defaulting to something
different than a system default?

Noone else does it, except maybe some old s390 drivers. We'll kill it then.

The rationale was that guest I/O delays depend on the I/O done by all other guests at the same time. So, in theory there is no need to schedule it on the guest---assuming hypercalls are fast enough it should be passed down to the host immediately and left to be scheduled together with all the other host I/O.

However, actual benchmarks show that this does not always hold (sometimes disastrously) so killing the elevator_init call is safe and is fine by me.


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