This test set the bar too high.
Just a couple of missed timers was enough to fail.
Change the test to more of a sanity check.
While we're here, run it for just 1s instead of 5s.
Prior to this change, on a 13" M1 MPB, with
stress -p 512 ./rate.test -test.run=QPS
I saw 90%+ failures.
After this change, I'm at 30k runs with no failures yet.
Fixes#3733
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This test is highly dependent on the accuracy of OS timers.
Reduce the number of failures by decreasing the required
accuracy from 0.999 to 0.995.
Also, switch from repeated time.Sleep to using a time.Ticker
for improved accuracy.
Updates #2727
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This was the proximate cause of #2579.
#2582 is a deeper fix, but this will remain
as a footgun, so may as well fix it too.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This is a simplified rate limiter geared for exactly our needs:
A fast, mono.Time-based rate limiter for use in tstun.
It was generated by stripping down the x/time/rate rate limiter
to just our needs and switching it to use mono.Time.
It removes one time.Now call per packet.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Package mono provides a fast monotonic time.
Its primary advantage is that it is fast:
It is approximately twice as fast as time.Now.
This is because time.Now uses two clock calls,
one for wall time and one for monotonic time.
We ask for the current time 4-6 times per network packet.
At ~50ns per call to time.Now, that's enough to show
up in CPU profiles.
Package mono is a first step towards addressing that.
It is designed to be a near drop-in replacement for package time.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Makes parsing 4.6x faster.
name old time/op new time/op delta
ParseInt-12 32.1ns ± 1% 6.9ns ± 2% -78.55% (p=0.000 n=10+9)
Signed-off-by: David Anderson <danderson@tailscale.com>
Go's time.Parse always allocates a FixedZone for time strings not in
UTC (ending in "Z"). This avoids that allocation, at the cost of
adding a cache.
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
