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Bug 1631822 - Use geometric mean for fastest TRR selection. r=tdsmith,dragana

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Differential Revision: https://phabricator.services.mozilla.com/D73358
This commit is contained in:
Nihanth Subramanya 2020-05-01 20:05:28 +00:00
parent 7745d09edf
commit de3f5af147
1 changed files with 11 additions and 6 deletions
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17
browser/components/doh/TRRPerformance.jsm
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@ -312,7 +312,6 @@ class TRRRacer {
*/
_getFastestTRRFromResults(results) {
// First, organize the results into a map of TRR -> array of times
// TODO: Consider uncached domains or not?
let TRRTimingMap = new Map();
for (let { trr, time } of results) {
if (!TRRTimingMap.has(trr)) {
@ -323,18 +322,24 @@ class TRRRacer {
}
}
// Loop through each TRR's array of times, compute the means, and remember
// the fastest TRR
// TODO: Do we want geometric means here?
// Loop through each TRR's array of times, compute the geometric means,
// and remember the fastest TRR. Geometric mean is a bit more forgiving
// in the presence of noise (anomalously high values).
// We don't need the full geometric mean, we simply calculate the arithmetic
// means in log-space and then compare those values.
let fastestTRR;
let fastestAverageTime = -1;
for (let trr of TRRTimingMap.keys()) {
let trrs = [...TRRTimingMap.keys()];
for (let trr of trrs) {
let times = TRRTimingMap.get(trr);
if (!times.length) {
continue;
}
let averageTime = times.reduce((a, b) => a + b) / times.length;
// Arithmetic mean in log space. Take log of (a + 1) to ensure we never
// take log(0) which would be -Infinity.
let averageTime =
times.map(a => Math.log(a + 1)).reduce((a, b) => a + b) / times.length;
if (fastestAverageTime == -1 || averageTime < fastestAverageTime) {
fastestAverageTime = averageTime;
fastestTRR = trr;