* (global): added --no-mem-optimization flag

This commit adds a new command-line argument that disables memory
optimizations AGH is using. These memory optimizations might be
necessary on low-memory devices, but they aren't free and there's a
performance hit (see #2044). Now they can be disabled - just pass
--no-mem-optimization when you run AGH or when you install the service
-- ./AdGuardHome -s install --no-mem-optimization

Closes: #2044

main.go

@@ -4,10 +4,6 @@
 package main
 
 import (
-	"os"
-	"runtime/debug"
-	"time"
-
 	"github.com/AdguardTeam/AdGuardHome/home"
 )
 
@@ -21,32 +17,5 @@ var channel = "release"
 var goarm = ""
 
 func main() {
-	memoryUsage()
-
 	home.Main(version, channel, goarm)
 }
-
-// memoryUsage implements a couple of not really beautiful hacks which purpose is to
-// make OS reclaim the memory freed by AdGuard Home as soon as possible.
-func memoryUsage() {
-	debug.SetGCPercent(10)
-
-	// madvdontneed: setting madvdontneed=1 will use MADV_DONTNEED
-	// instead of MADV_FREE on Linux when returning memory to the
-	// kernel. This is less efficient, but causes RSS numbers to drop
-	// more quickly.
-	_ = os.Setenv("GODEBUG", "madvdontneed=1")
-
-	// periodically call "debug.FreeOSMemory" so
-	// that the OS could reclaim the free memory
-	go func() {
-		ticker := time.NewTicker(15 * time.Second)
-		for {
-			select {
-			case t := <-ticker.C:
-				t.Second()
-				debug.FreeOSMemory()
-			}
-		}
-	}()
-}