On 06/21/2017 09:56 AM, Chris Peterson wrote:
On 6/21/17 8:06 AM, Boris Zbarsky wrote:
On 6/21/17 10:44 AM, Ehsan Akhgari wrote:
It seems like that we have an answer now in the bug!
https://bugzilla.mozilla.org/show_bug.cgi?id=1338651#c129
Just for clarity, so people don't have to read the whole bug,
changing the _path_ the build is at when it's compiled/linked results
in the huge observed performance difference. At least if I
understand the comments in the bug correctly.
i.e. Mike Shal's patch here fixed multiple 30% Talos regressions!
-: WORKSPACE ${WORKSPACE:=/home/worker/workspace}
+: WORKSPACE ${WORKSPACE:=/builds/slave/try-m64-0000000000000000000000}
Clearly we should try adding more zeroes!
Slightly more seriously, 20-30% is a rather big deal. If this *is* a
result of changing section offsets or whatever it was that glandium was
saying, it seems worth a look to see if we can squeeze any more of this
magic speedup sauce out of it by reordering things (or... something?).
At the very least, it would be good to detect when we're going back to
doing the bad thing, whatever that was, so that we don't have to infer
it from a Talos regression (that might not be quite as clear-cut next time.)
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