From 10c15a6548a27bbb51eb04082a11fd110a4642a5 Mon Sep 17 00:00:00 2001
From: Robert Schulze <robert@clickhouse.com>
Date: Mon, 17 Jul 2023 10:33:09 +0000
Subject: [PATCH] Refactor limit_jobs.cmake

---
 cmake/limit_jobs.cmake | 53 ++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 28 deletions(-)

diff --git a/cmake/limit_jobs.cmake b/cmake/limit_jobs.cmake
index 3a33b3b9989..b2a54fb8d1a 100644
--- a/cmake/limit_jobs.cmake
+++ b/cmake/limit_jobs.cmake
@@ -1,16 +1,14 @@
-# Usage:
-# set (MAX_COMPILER_MEMORY 2000 CACHE INTERNAL "") # In megabytes
-# set (MAX_LINKER_MEMORY 3500 CACHE INTERNAL "")
+# Usage from CMake:
+# set (MAX_COMPILER_MEMORY 2000 CACHE INTERNAL "") # megabyte
+# set (MAX_LINKER_MEMORY 3500 CACHE INTERNAL "") # megabyte
 # include (cmake/limit_jobs.cmake)
 
 cmake_host_system_information(RESULT TOTAL_PHYSICAL_MEMORY QUERY TOTAL_PHYSICAL_MEMORY) # Not available under freebsd
 cmake_host_system_information(RESULT NUMBER_OF_LOGICAL_CORES QUERY NUMBER_OF_LOGICAL_CORES)
 
-# 1 if not set
-option(PARALLEL_COMPILE_JOBS "Maximum number of concurrent compilation jobs" "")
-
-# 1 if not set
-option(PARALLEL_LINK_JOBS "Maximum number of concurrent link jobs" "")
+# Set to disable the automatic job-limiting
+option(PARALLEL_COMPILE_JOBS "Maximum number of concurrent compilation jobs" OFF)
+option(PARALLEL_LINK_JOBS "Maximum number of concurrent link jobs" OFF)
 
 if (NOT PARALLEL_COMPILE_JOBS AND TOTAL_PHYSICAL_MEMORY AND MAX_COMPILER_MEMORY)
     math(EXPR PARALLEL_COMPILE_JOBS ${TOTAL_PHYSICAL_MEMORY}/${MAX_COMPILER_MEMORY})
@@ -19,17 +17,10 @@ if (NOT PARALLEL_COMPILE_JOBS AND TOTAL_PHYSICAL_MEMORY AND MAX_COMPILER_MEMORY)
         set (PARALLEL_COMPILE_JOBS 1)
     endif ()
     if (NOT NUMBER_OF_LOGICAL_CORES OR PARALLEL_COMPILE_JOBS LESS NUMBER_OF_LOGICAL_CORES)
-        set (PARALLEL_COMPILE_JOBS_LESS TRUE)
+        set (PARALLEL_COMPILE_JOBS_UNDERUTILIZING TRUE)
     endif()
 endif ()
 
-if (PARALLEL_COMPILE_JOBS AND (NOT NUMBER_OF_LOGICAL_CORES OR PARALLEL_COMPILE_JOBS LESS NUMBER_OF_LOGICAL_CORES))
-    set(CMAKE_JOB_POOL_COMPILE compile_job_pool${CMAKE_CURRENT_SOURCE_DIR})
-    string (REGEX REPLACE "[^a-zA-Z0-9]+" "_" CMAKE_JOB_POOL_COMPILE ${CMAKE_JOB_POOL_COMPILE})
-    set_property(GLOBAL APPEND PROPERTY JOB_POOLS ${CMAKE_JOB_POOL_COMPILE}=${PARALLEL_COMPILE_JOBS})
-endif ()
-
-
 if (NOT PARALLEL_LINK_JOBS AND TOTAL_PHYSICAL_MEMORY AND MAX_LINKER_MEMORY)
     math(EXPR PARALLEL_LINK_JOBS ${TOTAL_PHYSICAL_MEMORY}/${MAX_LINKER_MEMORY})
 
@@ -37,7 +28,7 @@ if (NOT PARALLEL_LINK_JOBS AND TOTAL_PHYSICAL_MEMORY AND MAX_LINKER_MEMORY)
         set (PARALLEL_LINK_JOBS 1)
     endif ()
     if (NOT NUMBER_OF_LOGICAL_CORES OR PARALLEL_LINK_JOBS LESS NUMBER_OF_LOGICAL_CORES)
-        set (PARALLEL_LINK_JOBS_LESS TRUE)
+        set (PARALLEL_LINK_JOBS_UNDERUTILIZING TRUE)
     endif()
 endif ()
 
@@ -52,20 +43,26 @@ if (CMAKE_BUILD_TYPE_UC STREQUAL "RELWITHDEBINFO" AND ENABLE_THINLTO AND PARALLE
     set (PARALLEL_LINK_JOBS 2)
 endif()
 
+message(STATUS "System has ${NUMBER_OF_LOGICAL_CORES} logical cores and ${TOTAL_PHYSICAL_MEMORY} megabytes of memory. Building with ${PARALLEL_COMPILE_JOBS} compile jobs and ${PARALLEL_COMPILE_JOBS} linker jobs.")
+
+if (PARALLEL_COMPILE_JOBS OR PARALLEL_LINK_JOBS)
+    if (PARALLEL_COMPILE_JOBS_UNDERUTILIZING)
+        message(WARNING "The autocalculated compile jobs limit (${PARALLEL_COMPILE_JOBS}) underutilizes CPU cores (${NUMBER_OF_LOGICAL_CORES}). Set PARALLEL_COMPILE_JOBS to override.")
+    endif()
+    if (PARALLEL_LINK_JOBS_UNDERUTILIZING)
+        message(WARNING "The autocalculated link jobs limit (${PARALLEL_LINK_JOBS}) underutilizes CPU cores (${NUMBER_OF_LOGICAL_CORES}). Set PARALLEL_LINK_JOBS to override.")
+    endif()
+endif ()
+
+if (PARALLEL_COMPILE_JOBS AND (NOT NUMBER_OF_LOGICAL_CORES OR PARALLEL_COMPILE_JOBS LESS NUMBER_OF_LOGICAL_CORES))
+    set(CMAKE_JOB_POOL_COMPILE compile_job_pool${CMAKE_CURRENT_SOURCE_DIR})
+    string (REGEX REPLACE "[^a-zA-Z0-9]+" "_" CMAKE_JOB_POOL_COMPILE ${CMAKE_JOB_POOL_COMPILE})
+    set_property(GLOBAL APPEND PROPERTY JOB_POOLS ${CMAKE_JOB_POOL_COMPILE}=${PARALLEL_COMPILE_JOBS})
+endif ()
+
 if (PARALLEL_LINK_JOBS AND (NOT NUMBER_OF_LOGICAL_CORES OR PARALLEL_LINK_JOBS LESS NUMBER_OF_LOGICAL_CORES))
     set(CMAKE_JOB_POOL_LINK link_job_pool${CMAKE_CURRENT_SOURCE_DIR})
     string (REGEX REPLACE "[^a-zA-Z0-9]+" "_" CMAKE_JOB_POOL_LINK ${CMAKE_JOB_POOL_LINK})
     set_property(GLOBAL APPEND PROPERTY JOB_POOLS ${CMAKE_JOB_POOL_LINK}=${PARALLEL_LINK_JOBS})
 endif ()
 
-if (PARALLEL_COMPILE_JOBS OR PARALLEL_LINK_JOBS)
-    message(STATUS
-        "${CMAKE_CURRENT_SOURCE_DIR}: Have ${TOTAL_PHYSICAL_MEMORY} megabytes of memory.
-        Limiting concurrent linkers jobs to ${PARALLEL_LINK_JOBS} and compiler jobs to ${PARALLEL_COMPILE_JOBS} (system has ${NUMBER_OF_LOGICAL_CORES} logical cores)")
-    if (PARALLEL_COMPILE_JOBS_LESS)
-        message(WARNING "The autocalculated compile jobs limit (${PARALLEL_COMPILE_JOBS}) underutilizes CPU cores (${NUMBER_OF_LOGICAL_CORES}). Set PARALLEL_COMPILE_JOBS to override.")
-    endif()
-    if (PARALLEL_LINK_JOBS_LESS)
-        message(WARNING "The autocalculated link jobs limit (${PARALLEL_LINK_JOBS}) underutilizes CPU cores (${NUMBER_OF_LOGICAL_CORES}). Set PARALLEL_LINK_JOBS to override.")
-    endif()
-endif ()