5 files changed, 52 insertions, 10 deletions

diff --git a/ui/build/build.go b/ui/build/build.go
index 1c2d8648..de36dce9 100644
--- a/ui/build/build.go
+++ b/ui/build/build.go
@@ -46,8 +46,11 @@ func SetupOutDir(ctx Context, config Config) {
 
 var combinedBuildNinjaTemplate = template.Must(template.New("combined").Parse(`
 builddir = {{.OutDir}}
-pool local_pool
+{{if .UseRemoteBuild }}pool local_pool
  depth = {{.Parallel}}
+{{end -}}
+pool highmem_pool
+ depth = {{.HighmemParallel}}
 build _kati_always_build_: phony
 {{if .HasKatiSuffix}}subninja {{.KatiBuildNinjaFile}}
 subninja {{.KatiPackageNinjaFile}}
diff --git a/ui/build/config.go b/ui/build/config.go
index c0841713..9b19ede3 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -722,6 +722,33 @@ func (c *configImpl) Parallel() int {
 	return c.parallel
 }
 
+func (c *configImpl) HighmemParallel() int {
+	if i, ok := c.environ.GetInt("NINJA_HIGHMEM_NUM_JOBS"); ok {
+		return i
+	}
+
+	const minMemPerHighmemProcess = 8 * 1024 * 1024 * 1024
+	parallel := c.Parallel()
+	if c.UseRemoteBuild() {
+		// Ninja doesn't support nested pools, and when remote builds are enabled the total ninja parallelism
+		// is set very high (i.e. 500).  Using a large value here would cause the total number of running jobs
+		// to be the sum of the sizes of the local and highmem pools, which will cause extra CPU contention.
+		// Return 1/16th of the size of the local pool, rounding up.
+		return (parallel + 15) / 16
+	} else if c.totalRAM == 0 {
+		// Couldn't detect the total RAM, don't restrict highmem processes.
+		return parallel
+	} else if c.totalRAM <= 32*1024*1024*1024 {
+		// Less than 32GB of ram, restrict to 2 highmem processes
+		return 2
+	} else if p := int(c.totalRAM / minMemPerHighmemProcess); p < parallel {
+		// If less than 8GB total RAM per process, reduce the number of highmem processes
+		return p
+	}
+	// No restriction on highmem processes
+	return parallel
+}
+
 func (c *configImpl) TotalRAM() uint64 {
 	return c.totalRAM
 }
@@ -782,10 +809,11 @@ func (c *configImpl) UseRemoteBuild() bool {
 // gomacc) are run in parallel.  Note the parallelism of all other jobs is
 // still limited by Parallel()
 func (c *configImpl) RemoteParallel() int {
-	if v, ok := c.environ.Get("NINJA_REMOTE_NUM_JOBS"); ok {
-		if i, err := strconv.Atoi(v); err == nil {
-			return i
-		}
+	if !c.UseRemoteBuild() {
+		return 0
+	}
+	if i, ok := c.environ.GetInt("NINJA_REMOTE_NUM_JOBS"); ok {
+		return i
 	}
 	return 500
 }
diff --git a/ui/build/config_darwin.go b/ui/build/config_darwin.go
index 480d8d1f..fe74e31d 100644
--- a/ui/build/config_darwin.go
+++ b/ui/build/config_darwin.go
@@ -22,7 +22,7 @@ import (
 func detectTotalRAM(ctx Context) uint64 {
 	s, err := syscall.Sysctl("hw.memsize")
 	if err != nil {
-		ctx.Printf("Failed to get system memory size: %s")
+		ctx.Printf("Failed to get system memory size: %v", err)
 		return 0
 	}
 
@@ -32,7 +32,7 @@ func detectTotalRAM(ctx Context) uint64 {
 	}
 
 	if len(s) != 8 {
-		ctx.Printf("Failed to get system memory size, returned %d bytes, 8", len(s))
+		ctx.Printf("Failed to get system memory size, returned %d bytes, expecting 8 bytes", len(s))
 		return 0
 	}
 
diff --git a/ui/build/config_linux.go b/ui/build/config_linux.go
index 9e1bdc7f..162d372d 100644
--- a/ui/build/config_linux.go
+++ b/ui/build/config_linux.go
@@ -20,9 +20,8 @@ func detectTotalRAM(ctx Context) uint64 {
 	var info syscall.Sysinfo_t
 	err := syscall.Sysinfo(&info)
 	if err != nil {
-		ctx.Printf("Failed to get system memory size: %s")
+		ctx.Printf("Failed to get system memory size: %v", err)
 		return 0
 	}
-	memBytes := uint64(info.Totalram) * uint64(info.Unit)
-	return memBytes
+	return uint64(info.Totalram) * uint64(info.Unit)
 }
diff --git a/ui/build/environment.go b/ui/build/environment.go
index d8ff7f20..9bca7c06 100644
--- a/ui/build/environment.go
+++ b/ui/build/environment.go
@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strconv"
 	"strings"
 )
 
@@ -44,6 +45,17 @@ func (e *Environment) Get(key string) (string, bool) {
 	return "", false
 }
 
+// Get returns the int value associated with the key, and whether it exists
+// and is a valid int.
+func (e *Environment) GetInt(key string) (int, bool) {
+	if v, ok := e.Get(key); ok {
+		if i, err := strconv.Atoi(v); err == nil {
+			return i, true
+		}
+	}
+	return 0, false
+}
+
 // Set sets the value associated with the key, overwriting the current value
 // if it exists.
 func (e *Environment) Set(key, value string) {