Merge pull request ceph#56865 from zmc/cmake-sccache-max-jobs

cmake: Intelligently set job limits for sccache

Reviewed-by: Kefu Chai <[email protected]>

Author: tchaikov

CMakeLists.txt

@@ -85,17 +85,36 @@ endif(WITH_CCACHE)
 
 option(WITH_SCCACHE "Build with sccache.")
 if(WITH_SCCACHE)
-  if(CMAKE_C_COMPILER_LAUNCHER OR CMAKE_CXX_COMPILER_LAUNCHER)
-    message(WARNING "Compiler launcher already set. stop configuring sccache")
-  else()
-    find_program(SCCACHE_EXECUTABLE sccache)
-    if(NOT SCCACHE_EXECUTABLE)
-      message(FATAL_ERROR "Can't find sccache. Is it installed?")
+  find_program(SCCACHE_EXECUTABLE sccache)
+  if(NOT SCCACHE_EXECUTABLE)
+    message(FATAL_ERROR "Can't find sccache. Is it installed?")
+  endif()
+  if(NOT NINJA_MAX_COMPILE_JOBS)
+    if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.19")
+      execute_process(
+        COMMAND "sccache" "--dist-status"
+        OUTPUT_VARIABLE sccache_dist_status
+      )
+      string(
+        JSON sccache_cores
+        ERROR_VARIABLE sccache_dist_status_error
+        GET "${sccache_dist_status}" SchedulerStatus 1 num_cpus
+      )
+      string(FIND "${sccache_dist_status}" "disabled" find_result)
+      if(find_result EQUAL -1)
+        message(STATUS "Using sccache with distributed compilation. Effective cores: ${sccache_cores}")
+        set(NINJA_MAX_COMPILE_JOBS ${sccache_cores})
+        set(NINJA_MAX_LINK_JOBS ${sccache_cores})
+      else()
+        message(WARNING "Using sccache, but it is not configured for distributed complilation")
+      endif()
+    else()
+      message(WARNING "Using sccache, but cannot determine maximum job value since cmake version is <3.19")
     endif()
-    message(STATUS "Building with sccache: ${SCCACHE_EXECUTABLE}, SCCACHE_CONF=$ENV{SCCACHE_CONF}")
-    set(CMAKE_C_COMPILER_LAUNCHER ${SCCACHE_EXECUTABLE})
-    set(CMAKE_CXX_COMPILER_LAUNCHER ${SCCACHE_EXECUTABLE})
   endif()
+  message(STATUS "Building with sccache: ${SCCACHE_EXECUTABLE}, SCCACHE_CONF=$ENV{SCCACHE_CONF}")
+  set(CMAKE_C_COMPILER_LAUNCHER ${SCCACHE_EXECUTABLE})
+  set(CMAKE_CXX_COMPILER_LAUNCHER ${SCCACHE_EXECUTABLE})
 endif(WITH_SCCACHE)
 
 option(WITH_MANPAGE "Build man pages." ON)

cmake/modules/LimitJobs.cmake

@@ -4,16 +4,20 @@ set(MAX_LINK_MEM 4500 CACHE INTERNAL "maximum memory used by each linking job (i
 cmake_host_system_information(RESULT _num_cores QUERY NUMBER_OF_LOGICAL_CORES)
 cmake_host_system_information(RESULT _total_mem QUERY TOTAL_PHYSICAL_MEMORY)
 
-math(EXPR _avg_compile_jobs "${_total_mem} / ${MAX_COMPILE_MEM}")
-if(_avg_compile_jobs EQUAL 0)
-  set(_avg_compile_jobs 1)
-endif()
-if(_num_cores LESS _avg_compile_jobs)
-  set(_avg_compile_jobs ${_num_cores})
+if(NINJA_MAX_COMPILE_JOBS)
+  set(_avg_compile_jobs "${NINJA_MAX_COMPILE_JOBS}")
+else()
+  math(EXPR _avg_compile_jobs "${_total_mem} / ${MAX_COMPILE_MEM}")
+  if(_avg_compile_jobs EQUAL 0)
+    set(_avg_compile_jobs 1)
+  endif()
+  if(_num_cores LESS _avg_compile_jobs)
+    set(_avg_compile_jobs "${_num_cores}")
+  endif()
+  set(NINJA_MAX_COMPILE_JOBS "${_avg_compile_jobs}" CACHE STRING
+    "The maximum number of concurrent compilation jobs, for Ninja build system." FORCE)
+  mark_as_advanced(NINJA_MAX_COMPILE_JOBS)
 endif()
-set(NINJA_MAX_COMPILE_JOBS "${_avg_compile_jobs}" CACHE STRING
-  "The maximum number of concurrent compilation jobs, for Ninja build system." FORCE)
-mark_as_advanced(NINJA_MAX_COMPILE_JOBS)
 if(NINJA_MAX_COMPILE_JOBS)
   math(EXPR _heavy_compile_jobs "${_avg_compile_jobs} / 2")
   if(_heavy_compile_jobs EQUAL 0)
@@ -25,16 +29,20 @@ if(NINJA_MAX_COMPILE_JOBS)
   set(CMAKE_JOB_POOL_COMPILE avg_compile_job_pool)
 endif()
 
-math(EXPR _avg_link_jobs "${_total_mem} / ${MAX_LINK_MEM}")
-if(_avg_link_jobs EQUAL 0)
-  set(_avg_link_jobs 1)
-endif()
-if(_num_cores LESS _avg_link_jobs)
-  set(_avg_link_jobs ${_num_cores})
+if(NINJA_MAX_LINK_JOBS)
+  set(_avg_link_jobs "${NINJA_MAX_LINK_JOBS}")
+else()
+  math(EXPR _avg_link_jobs "${_total_mem} / ${MAX_LINK_MEM}")
+  if(_avg_link_jobs EQUAL 0)
+    set(_avg_link_jobs 1)
+  endif()
+  if(_num_cores LESS _avg_link_jobs)
+    set(_avg_link_jobs "${_num_cores}")
+  endif()
+  set(NINJA_MAX_LINK_JOBS "${_avg_link_jobs}" CACHE STRING
+    "The maximum number of concurrent link jobs, for Ninja build system." FORCE)
+  mark_as_advanced(NINJA_MAX_LINK_JOBS)
 endif()
-set(NINJA_MAX_LINK_JOBS "${_avg_link_jobs}" CACHE STRING
-  "The maximum number of concurrent link jobs, for Ninja build system." FORCE)
-mark_as_advanced(NINJA_MAX_LINK_JOBS)
 if(NINJA_MAX_LINK_JOBS)
   math(EXPR _heavy_link_jobs "${_avg_link_jobs} / 2")
   if(_heavy_link_jobs EQUAL 0)