615535 - Have a Ts run on Linux Talos with disabled barriers

Status: RESOLVED FIXED

(Release Engineering :: General, defect, P2)

Description

[Marco Bonardo [:mak]]

We'd like to have some Ts result from a Linux talos box with ext4 barriers disabled, to figure out if they play a role in the Ts regression we are seeing on the Places branch.

So, the request is to have 3-4 Ts runs of a Places branch changeset (http://hg.mozilla.org/projects/places/rev/080549b4c0f8 could be fine) on a linux ext4 box with barriers disabled.

Comment 1

[Marco Bonardo [:mak]]

This investigation is currently blocking the Places branch merge to central, thus requesting blocking an bumping up priority a bit.

Comment 2

[Chris AtLee [:catlee]]

Taking talos-r3-fed-003 out of the pool for this.

Comment 3

[Chris AtLee [:catlee]]

Remounted / with barriers off with

  # mount / -o remount,barrier=0

Ran Ts 3 times and got these values:

532.84, 522.47, 520.16

Comment 4

[Marco Bonardo [:mak]]

So, comparing with our results from the branch boxes (577.09±34.08), barriers are culprit for about 50ms

Comment 5

[Marco Bonardo [:mak]]

Thank you very much Chris, you've been very helpful. I think we are done with this measure.

Comment 6

[Chris AtLee [:catlee]]

And to compare...mount / -o remount,barrier=1

588.37, 590.11, 591.26.

Machine is back in the pool.

Comment 7

[Marco Bonardo [:mak]]

interesting this is a bit more than the 577 we had, so looks more like 60ms

Comment 8

[LegNeato]

As per today's meeting, beta 9 will be a time-based release. Marking these all betaN+. Please move it back to beta9+ if  you believe it MUST be in the next beta (ie: trunk is in an unshippable state without this)