Closed Bug 1618173 Opened 2 years ago Closed 2 years ago

TRR: We don't use DNS cache at all for the URL of DoH server


(Core :: Networking: DNS, defect, P1)




Tracking Status
firefox-esr68 --- unaffected
firefox73 --- unaffected
firefox74 + fixed
firefox75 + fixed


(Reporter: kershaw, Assigned: kershaw)




(Keywords: regression, Whiteboard: [necko-triaged])


(1 file)

In our current implementation, NS_HTTP_REFRESH_DNS [1] is set to the http channel that connects to the DoH server.
This causes the URL is resolved every time without using the DNS cache.


Assignee: nobody → kershaw
Priority: -- → P1
Whiteboard: [necko-triaged]
Pushed by
Don't set NS_HTTP_REFRESH_DNS for TRR service channel r=valentin
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla75

[Tracking Requested - why for this release]:

This fixes a performance regression in Firefox 74.
Should be nominated for beta uplift.

Comment on attachment 9129154 [details]
Bug 1618173 - Don't set NS_HTTP_REFRESH_DNS for TRR service channel

Beta/Release Uplift Approval Request

  • User impact if declined: Performance of DNS request is a bit dropped.
  • Is this code covered by automated tests?: No
  • Has the fix been verified in Nightly?: Yes
  • Needs manual test from QE?: No
  • If yes, steps to reproduce:
  • List of other uplifts needed: None
  • Risk to taking this patch: Low
  • Why is the change risky/not risky? (and alternatives if risky): The patch is quite simple and it only affects whether to read data from DNS cache.
  • String changes made/needed: N/A
Attachment #9129154 - Flags: approval-mozilla-beta?

Comment on attachment 9129154 [details]
Bug 1618173 - Don't set NS_HTTP_REFRESH_DNS for TRR service channel

Perf gain, low risk patch, uplift approved for 74 beta 9, thanks.

Attachment #9129154 - Flags: approval-mozilla-beta? → approval-mozilla-beta+

== Change summary for alert #25140 (as of Thu, 27 Feb 2020 08:52:38 GMT) ==


27% raptor-tp6m-instagram-geckoview-cold loadtime android-hw-p2-8-0-android-aarch64 pgo 2,070.04 -> 1,520.33
16% raptor-tp6m-bbc-geckoview-cold loadtime android-hw-g5-7-0-arm7-api-16 pgo 4,550.15 -> 3,800.50
14% raptor-tp6m-instagram-geckoview-cold android-hw-p2-8-0-android-aarch64 pgo 556.69 -> 477.65
11% raptor-tp6-microsoft-firefox-cold loadtime macosx1014-64-shippable opt 1,198.08 -> 1,071.08
10% raptor-tp6m-instagram-geckoview-cold loadtime android-hw-g5-7-0-arm7-api-16 pgo 3,328.58 -> 2,983.38
2% raptor-tp6-office-firefox-cold linux64-shippable-qr opt 462.94 -> 451.49
2% raptor-tp6-office-firefox-cold fcp linux64-shippable-qr opt 453.88 -> 442.92

For up to date results, see:

Duplicate of this bug: 1605775
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