Re: [ANNOUNCE] WireGuard Snapshot `0.0.20180620` Available

["Jason A. Donenfeld" <Jason@zx2c4.com>]

Hey Lonnie,

Thanks for helping to debug this.

On Thu, Jun 21, 2018 at 12:37 AM Lonnie Abelbeck
<lists@lonnie.abelbeck.com> wrote:
> Hunk #1 only does the trick, though performance is ever so slightly slowe=
r than before overall.

It's good to hear that hunks #2 and #3 don't have much an effect,
though it does still seem to have _some_ effect.

Looks like hunk 1 is rather worrisome though. Can you try out
https://=D7=90.cc/eaxxpxbB and let me know if it has any effect?

> Is this issue because our project uses CONFIG_PREEMPT=3Dy ?

Yes, generally, preemption is good for latency but bad for throughput.
I was trying to make the queues a bit more preemption friendly, but
this seemed to have killed performance, so I'll be revisiting this,
because I don't want to make things worse than before.

I find it very strange that 20180531 is still faster than the last
patch I sent you. The only other difference along the hot path,
besides the last patch I sent you, between the two snapshots is
https://git.zx2c4.com/WireGuard/patch/?id=3Db7b193f499d4acd8a620163ec358c08=
30e856c9e
and this is _removing_ code, so I'd think this would actually
contribute to a speed increase, not a slight decrease. Are you sure
the benchmark conditions were the same in other respects?

Jason