>> If several different goroutines decide to wake up the polling >> goroutine before the polling goroutine wakes up, they will each write >> a single byte
Wondering, with the introduction of "netpollWakeSig", does it still hold true? Thanks. On Tuesday, July 11, 2023 at 9:00:36 AM UTC+8 Ian Lance Taylor wrote: > On Mon, Jul 10, 2023 at 6:10 AM shaouai <aou...@gmail.com> wrote: > > > > In the implementation of the Go netpoller, `netpollBreak()` attempts to > write 1 byte to `netpollBreakWr`, whereas `netpoll()` reads up to 16 bytes > from `netpollBreakRd`, why 16 bytes rather than 1 byte? > > > > write up to 1 byte: > https://cs.opensource.google/go/go/+/refs/tags/go1.20.5:src/runtime/netpoll_epoll.go;l=77;drc=c7cc2b94c63af610a29b1b48cfbfb87cb8abf05b > > > > read up to 16 bytes: > https://cs.opensource.google/go/go/+/refs/tags/go1.20.5:src/runtime/netpoll_epoll.go;l=146;drc=c7cc2b94c63af610a29b1b48cfbfb87cb8abf05b > > A single byte will wake up a goroutine sleeping in netpoll, so there > is no reason to write more than one byte. > > If several different goroutines decide to wake up the polling > goroutine before the polling goroutine wakes up, they will each write > a single byte, and they will all be satisfied by a single wakeup. > And, if we don't read all those bytes, there will still be bytes in > the pipe and we'll wake up the next time around the poll loop even if > we don't have to. So we try to read all of their wakeup bytes at > once. The number 16 is arbitrary, based on the assumption that it's > not all that likely that more than 16 goroutines will try to wake up > the poller simultaneously. > > Ian > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/8a3ae80e-1e78-441d-8c9a-c99e94e3c2c9n%40googlegroups.com.
