Re: more data: SCHED_ULE+PREEMPTION is the problem

[George Mitchell]

On 04/07/18 10:18, Peter wrote:
> [...]
> B. Findings:
> 
> 1. Filesystem
> 
> I could never reproduce this when reading from plain UFS. Only when
> reading from ZFS (direct or via l2arc).
> [...]
My consistent way of reproducing the problem was to run ports/misc/dnetc
while trying to buildworld/buildkernel.  But I was always building on a
UFS partition.  I don't know why your results would be different.
-- George



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Re: kern.sched.quantum: Creepy, sadistic scheduler

[Julian Elischer]

On 7/4/18 10:21 pm, Peter wrote:

Julian Elischer wrote:
for a single CPU you really should compile a kernel with SMP turned 
off

and 4BSD scheduler.

ULE is just trying too hard to do stuff you don't need.


Julian,

if we agree on this, I am fine.
(This implies that SCHED_4BSD will *not* be retired for an 
indefinite time!)


There is no reason to retire it.
We implemented a scheduler interface that both schedulers stick to.



I tested yesterday, and SCHED_4BSD doesn't show the annoying behaviour.
SMP seems to be no problem (and I need that), but PREEMPTION is 
definitely related to the problem (see my other message sent now).


P.
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