On Tue, Jan 17, 2017 at 12:04 PM, Matthew Miller
On Tue, Jan 17, 2017 at 04:38:31PM +0100, Jiri Eischmann wrote:
> I briefly spoke with Jiri Hladky, the manager of the FS perf team in
> Red Hat, and he says that deadline is clearly better for SSD. Results
> for rotating disks are mixed, but he'd still prefer deadline there,
> too. He can provide more detailed info if we need it.
It's my understanding that CFQ is better in the case where you a) have
a single spinning disk with b) mixed workload on top of that and c)
care about overall throughput more than latency. An example might be if
you are a budget hosting provider and are running multiple VMs on
single-disk servers. If is preferred for lower latency on desktops, and
is overall preferred for servers (a win on RAID, on SSD, and even on
single-disk systems in many cases), switching to as across-the-board
default deadline seems like the straightforward choice.
I guess the next step is to engage the kernel team, and possibly FESCo
since this is obviously a big engineering steering decision. And
someone other than me can decide if this should be a Change.
That is a somewhat odd suggestion. It's a runtime tunable for a
reason. No default will ever work for 100% of the cases Fedora may be
used in. Rather than go through all the effort of making a decision
for all of Fedora at the FESCo level, I would prefer the Workgroups
look at what their target machine types are and come up with a default
they would prefer to see. Then they can work on setting it at boot
via an Edition specific setting.