[Ksummit-discuss] [TECH TOPIC] benchmarking and performance trends

[Chris Mason <clm@fb.com>]

Hi everyone,

I know I never get bored of graphs comparing old/new, but I feel guilty
suggesting this one yet again.  Still, I think it's important for the
people trying to push new kernels into production to have a chance to
talk about the problems we've hit, and/or the changes that have made
life easier.

We're starting to push 4.0 into prod (122 hosts almost counts), and I'm
sure we'll backport some wins from 4.2+.  I'm hoping to make this a
collection point for other benchmarking war stories.  Our biggest gains
right now are coming from scsi-mq, and early benchmarks show 4.2 has a
boost that I'm hoping are from the futex locking improvements.

It ties in a little with the new interfaces applications may be able to use
(restartable sequences etc topic), and I want to ask the broad question of
"are we doing enough to prevent performance regressions".

We have a long list of people involved on the Facebook side, Jens at the
very least can talk about the scsi/block-mq benchmarks.  I'd love to hear
Fengguang's thoughts as well.

-chris