I'm working on an embedded device with 512 MiB of RAM. When I start a go
executable compiled with gccgo, it allocates over 800-900 MiB of memory
(VmData) right off the bat. This is around 180% of the memory available on
the device. I would like to reduce this to a value that is reasonable for
my device, but after hours of research, I cannot pinpoint where this
memory is being allocated, what it is for, nor how I can tweak the amount.
I'm cross compiling to i686 on ubuntu with i686-linux-gnu like so:
> #!/bin/bash
>
> TOOLCHAIN_PREFIX=i686-linux-gnu
> OPTIMIZATION_FLAG="-O3"
>
> CGO_ENABLED=1 \
> CC=${TOOLCHAIN_PREFIX}-gcc-8 \
> CXX=${TOOLCHAIN_PREFIX}-g++-8 \
> AR=${TOOLCHAIN_PREFIX}-ar \
> GCCGO=${TOOLCHAIN_PREFIX}-gccgo-8 \
> CGO_CFLAGS="-g ${OPTIMIZATION_FLAG}" \
> CGO_CPPFLAGS="" \
> CGO_CXXFLAGS="-g ${OPTIMIZATION_FLAG}" \
> CGO_FFLAGS="-g ${OPTIMIZATION_FLAG}" \
> CGO_LDFLAGS="-g ${OPTIMIZATION_FLAG}" \
> GOOS=linux \
> GOARCH=386 \
> go build -x \
> -compiler=gccgo \
> -gccgoflags=all="-static -g ${OPTIMIZATION_FLAG}" \
> $1
My gcc version is 8.2.0:
> $ i686-linux-gnu-gccgo-8 --version
> i686-linux-gnu-gccgo-8 (Ubuntu 8.2.0-1ubuntu2~18.04) 8.2.0
> Copyright (C) 2018 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is
NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.
The go executable that allocates 800-900 MiB of RAM is:
> package main
>
> import (
> "fmt"
> "time"
> )
>
> func main() {
> fmt.Println("hello world")
> time.Sleep(1000000000 * 5)
> }
I've played with the GOGC environment variable, but that only makes VmData
wiggle a few MiB one way or the other. I also tried looking through the
gccgo/libgo source code, but I got lost quickly. If anyone could set me on
the right path, I would be grateful.
