We were seeing our Elixir/Phoenix servers crash after ~1000 simultaneous connections.
Also, we had to change the tcp_keepalive_time and file-max
sysctl -w net.ipv4.tcp_keepalive_time=250 fs.file-max=1024000
It looks like +K was removed into OTP 21 and +A may have less impact now with the introduction of the dirty scheduler. +Q appears to default to 65536 so maybe that’s not needed anymore?
It would be wonderful if the vm settings I used weren’t needed anymore – it was miserable and confusing. Also, there was very little written about it, so there was a bunch of guessing and hoping on my part.
+sbwt none
+sbwtdcpu none
+sbwtdio none
I think the import parts were these one above. Do you know much about those settings, @mattbaker? I’d love to know what I was changing – at the time, it felt like reciting a magical incantation.
