From 816a6e68e52afe7dbe5ad0c785528a3864a3cfb0 Mon Sep 17 00:00:00 2001 From: Sam Lantinga Date: Mon, 23 Apr 2018 17:10:36 -0700 Subject: [PATCH] Added support for adjusting thread priorities using Linux RealtimeKit Michael Sartain This is a quick pass at adding Linux RealtimeKit thread priority support to SDL. It allows me to bump the thread priority to high without root privileges or setting any caps, etc. rtkit readme here: http://git.0pointer.net/rtkit.git/tree/README --- src/thread/pthread/SDL_systhread.c | 70 +++++++++++++++++++++++++++++- test/testthread.c | 31 +++++++++++++ 2 files changed, 99 insertions(+), 2 deletions(-) diff --git a/src/thread/pthread/SDL_systhread.c b/src/thread/pthread/SDL_systhread.c index 035484085..3abb4da13 100644 --- a/src/thread/pthread/SDL_systhread.c +++ b/src/thread/pthread/SDL_systhread.c @@ -34,6 +34,9 @@ #include #include #include +#include + +#include "../../core/linux/SDL_dbus.h" #endif /* __LINUX__ */ #if defined(__LINUX__) || defined(__MACOSX__) || defined(__IPHONEOS__) @@ -43,6 +46,7 @@ #endif #endif +#include "SDL_log.h" #include "SDL_platform.h" #include "SDL_thread.h" #include "../SDL_thread_c.h" @@ -180,6 +184,60 @@ SDL_ThreadID(void) return ((SDL_threadID) pthread_self()); } +/* d-bus queries to org.freedesktop.RealtimeKit1. */ +#if SDL_USE_LIBDBUS + +#define RTKIT_DBUS_NODE "org.freedesktop.RealtimeKit1" +#define RTKIT_DBUS_PATH "/org/freedesktop/RealtimeKit1" +#define RTKIT_DBUS_INTERFACE "org.freedesktop.RealtimeKit1" + +static pthread_once_t rtkit_initialize_once = PTHREAD_ONCE_INIT; +static Sint32 rtkit_min_nice_level = -20; + +static void +rtkit_initialize() +{ + SDL_DBusContext *dbus = SDL_DBus_GetContext(); + + /* Try getting minimum nice level: this is often greater than PRIO_MIN (-20). */ + if (!SDL_DBus_QueryPropertyOnConnection(dbus->system_conn, RTKIT_DBUS_NODE, RTKIT_DBUS_PATH, RTKIT_DBUS_INTERFACE, "MinNiceLevel", + DBUS_TYPE_INT32, &rtkit_min_nice_level)) { + rtkit_min_nice_level = -20; + } +} + +static SDL_bool +rtkit_setpriority(pid_t thread, int nice_level) +{ + Uint64 ui64 = (Uint64)thread; + Sint32 si32 = (Sint32)nice_level; + SDL_DBusContext *dbus = SDL_DBus_GetContext(); + + pthread_once(&rtkit_initialize_once, rtkit_initialize); + + if (si32 < rtkit_min_nice_level) + si32 = rtkit_min_nice_level; + + if (!SDL_DBus_CallMethodOnConnection(dbus->system_conn, + RTKIT_DBUS_NODE, RTKIT_DBUS_PATH, RTKIT_DBUS_INTERFACE, "MakeThreadHighPriority", + DBUS_TYPE_UINT64, &ui64, DBUS_TYPE_INT32, &si32, DBUS_TYPE_INVALID, + DBUS_TYPE_INVALID)) { + return SDL_FALSE; + } + + return SDL_TRUE; +} + +#else + +static SDL_bool +rtkit_setpriority(pid_t thread, int nice_level) +{ + return SDL_FALSE; +} + +#endif /* !SDL_USE_LIBDBUS */ + int SDL_SYS_SetThreadPriority(SDL_ThreadPriority priority) { @@ -188,6 +246,7 @@ SDL_SYS_SetThreadPriority(SDL_ThreadPriority priority) return 0; #elif __LINUX__ int value; + pid_t thread = syscall(SYS_gettid); if (priority == SDL_THREAD_PRIORITY_LOW) { value = 19; @@ -196,15 +255,22 @@ SDL_SYS_SetThreadPriority(SDL_ThreadPriority priority) } else { value = 0; } - if (setpriority(PRIO_PROCESS, syscall(SYS_gettid), value) < 0) { + if (setpriority(PRIO_PROCESS, thread, value) < 0) { /* Note that this fails if you're trying to set high priority and you don't have root permission. BUT DON'T RUN AS ROOT! You can grant the ability to increase thread priority by running the following command on your application binary: sudo setcap 'cap_sys_nice=eip' + + Let's try setting priority with RealtimeKit... + + README and sample code at: + http://git.0pointer.net/rtkit.git */ - return SDL_SetError("setpriority() failed"); + if (rtkit_setpriority(thread, value) == SDL_FALSE) { + return SDL_SetError("setpriority() failed"); + } } return 0; #else diff --git a/test/testthread.c b/test/testthread.c index cdccfc499..efba681e8 100644 --- a/test/testthread.c +++ b/test/testthread.c @@ -20,6 +20,7 @@ static SDL_TLSID tls; static int alive = 0; +static int testprio = 0; /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */ static void @@ -29,14 +30,36 @@ quit(int rc) exit(rc); } +static const char * +getprioritystr(SDL_ThreadPriority priority) +{ + switch(priority) + { + case SDL_THREAD_PRIORITY_LOW: return "SDL_THREAD_PRIORITY_LOW"; + case SDL_THREAD_PRIORITY_NORMAL: return "SDL_THREAD_PRIORITY_NORMAL"; + case SDL_THREAD_PRIORITY_HIGH: return "SDL_THREAD_PRIORITY_HIGH"; + } + + return "???"; +} + int SDLCALL ThreadFunc(void *data) { + SDL_ThreadPriority prio = SDL_THREAD_PRIORITY_NORMAL; + SDL_TLSSet(tls, "baby thread", NULL); SDL_Log("Started thread %s: My thread id is %lu, thread data = %s\n", (char *) data, SDL_ThreadID(), (const char *)SDL_TLSGet(tls)); while (alive) { SDL_Log("Thread '%s' is alive!\n", (char *) data); + + if (testprio) { + SDL_Log("SDL_SetThreadPriority(%s):%d\n", getprioritystr(prio), SDL_SetThreadPriority(prio)); + if (++prio > SDL_THREAD_PRIORITY_HIGH) + prio = SDL_THREAD_PRIORITY_LOW; + } + SDL_Delay(1 * 1000); } SDL_Log("Thread '%s' exiting!\n", (char *) data); @@ -55,6 +78,7 @@ killed(int sig) int main(int argc, char *argv[]) { + int arg = 1; SDL_Thread *thread; /* Enable standard application logging */ @@ -66,6 +90,13 @@ main(int argc, char *argv[]) return (1); } + while (argv[arg] && *argv[arg] == '-') { + if (SDL_strcmp(argv[arg], "--prio") == 0) { + testprio = 1; + } + ++arg; + } + tls = SDL_TLSCreate(); SDL_assert(tls); SDL_TLSSet(tls, "main thread", NULL);