1379126 - Filtering in CachePerfStats::MMA::AddValue is too strict

Status: RESOLVED FIXED

(Core :: Networking: Cache, enhancement)

Description

[Michal Novotny [:michal]]

Filtering based on max difference avg/4 + 2*stddev seems to be too strict. It's applied only on high values, so any low value pulls the average down. We include values from events that spent up to 5 event cycles in the queue, so we need to be more flexible here.

Comment 1

[Michal Novotny [:michal]]

Attachment: fix

Filtering of the values is now more relaxed. Also, stats for IO_WRITE isn't used in CachePerfStats::IsCacheSlow for detecting slow cache. Writes have low priority and it's normal that they are delayed a lot, but this doesn't necessarily affect opening cache entries.

Comment 2

[Valentin Gosu [:valentin] (he/him)]

Comment on attachment 8884263 [details] [diff] [review]
fix

Review of attachment 8884263 [details] [diff] [review]:
-----------------------------------------------------------------

nit: It's worth adding comments on why we ignore the write operations from the cache speed estimation.

Comment 3

[Michal Novotny [:michal]]

Attachment: patch v2 - added comment

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/0c098eb60dd1
Filtering in CachePerfStats::MMA::AddValue is too strict, r=valentin

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/0c098eb60dd1