Commit graph

5 commits

Author SHA1 Message Date
Jason A. Donenfeld c69481f1b3 device: disable waitpool tests
This code is stable, and the test is finicky, especially on high core
count systems, so just disable it.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2021-02-22 15:26:47 +01:00
Josh Bleecher Snyder d117d42ae7 device: run fewer trials in TestWaitPool when race detector enabled
On a many-core machine with the race detector enabled,
this test can take several minutes to complete.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-02-09 18:28:58 +01:00
Jason A. Donenfeld 6ac1240821 device: do not attach finalizer to non-returned object
Before, the code attached a finalizer to an object that wasn't returned,
resulting in immediate garbage collection. Instead return the actual
pointer.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2021-02-09 15:37:04 +01:00
Jason A. Donenfeld c3bde5f590 device: benchmark the waitpool to compare it to the prior channels
Here is the old implementation:

    type WaitPool struct {
        c chan interface{}
    }

    func NewWaitPool(max uint32, new func() interface{}) *WaitPool {
        p := &WaitPool{c: make(chan interface{}, max)}
        for i := uint32(0); i < max; i++ {
            p.c <- new()
        }
        return p
    }

    func (p *WaitPool) Get() interface{} {
        return <- p.c
    }

    func (p *WaitPool) Put(x interface{}) {
        p.c <- x
    }

It performs worse than the new one:

    name         old time/op  new time/op  delta
    WaitPool-16  16.4µs ± 5%  15.1µs ± 3%  -7.86%  (p=0.008 n=5+5)

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2021-02-03 16:59:29 +01:00
Jason A. Donenfeld 4846070322 device: use a waiting sync.Pool instead of a channel
Channels are FIFO which means we have guaranteed cache misses.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2021-02-02 19:32:13 +01:00