/* $Id: sched-linux.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */ /** @file * IPRT - Scheduling, POSIX. */ /* * Copyright (C) 2006-2019 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the * VirtualBox OSE distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. */ /* * !WARNING! * * When talking about lowering and raising priority, we do *NOT* refer to * the common direction priority values takes on unix systems (lower means * higher). So, when we raise the priority of a linux thread the nice * value will decrease, and when we lower the priority the nice value * will increase. Confusing, right? * * !WARNING! */ /** @def THREAD_LOGGING * Be very careful with enabling this, it may cause deadlocks when combined * with the 'thread' logging prefix. */ #ifdef DOXYGEN_RUNNING # define THREAD_LOGGING #endif /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #define LOG_GROUP RTLOGGROUP_THREAD #include #include #include #include #include #include #include #include #include #include #include #include #include "internal/sched.h" #include "internal/thread.h" /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** Array scheduler attributes corresponding to each of the thread types. * @internal */ typedef struct PROCPRIORITYTYPE { /** For sanity include the array index. */ RTTHREADTYPE enmType; /** The thread priority or nice delta - depends on which priority type. */ int iPriority; } PROCPRIORITYTYPE; /** * Configuration of one priority. * @internal */ typedef struct { /** The priority. */ RTPROCPRIORITY enmPriority; /** The name of this priority. */ const char *pszName; /** The process nice value. */ int iNice; /** The delta applied to the iPriority value. */ int iDelta; /** Array scheduler attributes corresponding to each of the thread types. */ const PROCPRIORITYTYPE *paTypes; } PROCPRIORITY; /** * Saved priority settings * @internal */ typedef struct { /** Process priority. */ int iPriority; /** Process level. */ struct sched_param SchedParam; /** Process level. */ int iPolicy; /** pthread level. */ struct sched_param PthreadSchedParam; /** pthread level. */ int iPthreadPolicy; } SAVEDPRIORITY, *PSAVEDPRIORITY; /********************************************************************************************************************************* * Global Variables * *********************************************************************************************************************************/ /** * Deltas for a process in which we are not restricted * to only be lowering the priority. */ static const PROCPRIORITYTYPE g_aTypesLinuxFree[RTTHREADTYPE_END] = { { RTTHREADTYPE_INVALID, -999999999 }, { RTTHREADTYPE_INFREQUENT_POLLER, +3 }, { RTTHREADTYPE_MAIN_HEAVY_WORKER, +2 }, { RTTHREADTYPE_EMULATION, +1 }, { RTTHREADTYPE_DEFAULT, 0 }, { RTTHREADTYPE_GUI, 0 }, { RTTHREADTYPE_MAIN_WORKER, 0 }, { RTTHREADTYPE_VRDP_IO, -1 }, { RTTHREADTYPE_DEBUGGER, -1 }, { RTTHREADTYPE_MSG_PUMP, -2 }, { RTTHREADTYPE_IO, -3 }, { RTTHREADTYPE_TIMER, -4 } }; /** * Deltas for a process in which we are restricted and can only lower the priority. */ static const PROCPRIORITYTYPE g_aTypesLinuxRestricted[RTTHREADTYPE_END] = { { RTTHREADTYPE_INVALID, -999999999 }, { RTTHREADTYPE_INFREQUENT_POLLER, +3 }, { RTTHREADTYPE_MAIN_HEAVY_WORKER, +2 }, { RTTHREADTYPE_EMULATION, +1 }, { RTTHREADTYPE_DEFAULT, 0 }, { RTTHREADTYPE_GUI, 0 }, { RTTHREADTYPE_MAIN_WORKER, 0 }, { RTTHREADTYPE_VRDP_IO, 0 }, { RTTHREADTYPE_DEBUGGER, 0 }, { RTTHREADTYPE_MSG_PUMP, 0 }, { RTTHREADTYPE_IO, 0 }, { RTTHREADTYPE_TIMER, 0 } }; /** * All threads have the same priority. * * This is typically chosen when we find that we can't raise the priority * to the process default of a thread created by a low priority thread. */ static const PROCPRIORITYTYPE g_aTypesLinuxFlat[RTTHREADTYPE_END] = { { RTTHREADTYPE_INVALID, -999999999 }, { RTTHREADTYPE_INFREQUENT_POLLER, 0 }, { RTTHREADTYPE_MAIN_HEAVY_WORKER, 0 }, { RTTHREADTYPE_EMULATION, 0 }, { RTTHREADTYPE_DEFAULT, 0 }, { RTTHREADTYPE_GUI, 0 }, { RTTHREADTYPE_MAIN_WORKER, 0 }, { RTTHREADTYPE_VRDP_IO, 0 }, { RTTHREADTYPE_DEBUGGER, 0 }, { RTTHREADTYPE_MSG_PUMP, 0 }, { RTTHREADTYPE_IO, 0 }, { RTTHREADTYPE_TIMER, 0 } }; /** * Process and thread level priority, full access at thread level. */ static const PROCPRIORITY g_aUnixConfigs[] = { { RTPROCPRIORITY_FLAT, "Flat", 0, 0, g_aTypesLinuxFlat }, { RTPROCPRIORITY_LOW, "Low", 9, 9, g_aTypesLinuxFree }, { RTPROCPRIORITY_LOW, "Low", 9, 9, g_aTypesLinuxFlat }, { RTPROCPRIORITY_LOW, "Low", 15, 15, g_aTypesLinuxFree }, { RTPROCPRIORITY_LOW, "Low", 15, 15, g_aTypesLinuxFlat }, { RTPROCPRIORITY_LOW, "Low", 17, 17, g_aTypesLinuxFree }, { RTPROCPRIORITY_LOW, "Low", 17, 17, g_aTypesLinuxFlat }, { RTPROCPRIORITY_LOW, "Low", 19, 19, g_aTypesLinuxFlat }, { RTPROCPRIORITY_LOW, "Low", 9, 9, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_LOW, "Low", 15, 15, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_LOW, "Low", 17, 17, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_NORMAL, "Normal", 0, 0, g_aTypesLinuxFree }, { RTPROCPRIORITY_NORMAL, "Normal", 0, 0, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_NORMAL, "Normal", 0, 0, g_aTypesLinuxFlat }, { RTPROCPRIORITY_HIGH, "High", -9, -9, g_aTypesLinuxFree }, { RTPROCPRIORITY_HIGH, "High", -7, -7, g_aTypesLinuxFree }, { RTPROCPRIORITY_HIGH, "High", -5, -5, g_aTypesLinuxFree }, { RTPROCPRIORITY_HIGH, "High", -3, -3, g_aTypesLinuxFree }, { RTPROCPRIORITY_HIGH, "High", -1, -1, g_aTypesLinuxFree }, { RTPROCPRIORITY_HIGH, "High", -9, -9, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_HIGH, "High", -7, -7, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_HIGH, "High", -5, -5, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_HIGH, "High", -3, -3, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_HIGH, "High", -1, -1, g_aTypesLinuxRestricted }, { RTPROCPRIORITY_HIGH, "High", -9, -9, g_aTypesLinuxFlat }, { RTPROCPRIORITY_HIGH, "High", -7, -7, g_aTypesLinuxFlat }, { RTPROCPRIORITY_HIGH, "High", -5, -5, g_aTypesLinuxFlat }, { RTPROCPRIORITY_HIGH, "High", -3, -3, g_aTypesLinuxFlat }, { RTPROCPRIORITY_HIGH, "High", -1, -1, g_aTypesLinuxFlat } }; /** * The dynamic default priority configuration. * * This will be recalulated at runtime depending on what the * system allow us to do and what the current priority is. */ static PROCPRIORITY g_aDefaultPriority = { RTPROCPRIORITY_LOW, "Default", 0, 0, g_aTypesLinuxRestricted }; /** Pointer to the current priority configuration. */ static const PROCPRIORITY *g_pProcessPriority = &g_aDefaultPriority; /** Set if we can raise the priority of a thread beyond the default. * * It might mean we have the CAP_SYS_NICE capability or that the * process's RLIMIT_NICE is higher than the priority of the thread * calculating the defaults. */ static bool g_fCanRaisePriority = false; /** Set if we can restore the priority after having temporarily lowered or raised it. */ static bool g_fCanRestorePriority = false; /** Set if we can NOT raise the priority to the process default in a thread * created by a thread running below the process default. */ static bool g_fScrewedUpMaxPriorityLimitInheritance = true; /** The highest priority we can set. */ static int g_iMaxPriority = 0; /** The lower priority we can set. */ static int g_iMinPriority = 19; /** Set when we've successfully determined the capabilities of the process and kernel. */ static bool g_fInitialized = false; /********************************************************************************************************************************* * Internal Functions * *********************************************************************************************************************************/ /** * Saves all the scheduling attributes we can think of. */ static void rtSchedNativeSave(PSAVEDPRIORITY pSave) { memset(pSave, 0xff, sizeof(*pSave)); errno = 0; pSave->iPriority = getpriority(PRIO_PROCESS, 0 /* current process */); Assert(errno == 0); errno = 0; sched_getparam(0 /* current process */, &pSave->SchedParam); Assert(errno == 0); errno = 0; pSave->iPolicy = sched_getscheduler(0 /* current process */); Assert(errno == 0); int rc = pthread_getschedparam(pthread_self(), &pSave->iPthreadPolicy, &pSave->PthreadSchedParam); Assert(rc == 0); NOREF(rc); } /** * Restores scheduling attributes. * Most of this won't work right, but anyway... */ static void rtSchedNativeRestore(PSAVEDPRIORITY pSave) { setpriority(PRIO_PROCESS, 0, pSave->iPriority); sched_setscheduler(0, pSave->iPolicy, &pSave->SchedParam); sched_setparam(0, &pSave->SchedParam); pthread_setschedparam(pthread_self(), pSave->iPthreadPolicy, &pSave->PthreadSchedParam); } /** * Starts a worker thread and wait for it to complete. * We cannot use RTThreadCreate since we're already owner of the RW lock. */ static int rtSchedRunThread(void *(*pfnThread)(void *pvArg), void *pvArg) { /* * Create the thread. */ pthread_t Thread; int rc = pthread_create(&Thread, NULL, pfnThread, pvArg); if (!rc) { /* * Wait for the thread to finish. */ void *pvRet = (void *)-1; do { rc = pthread_join(Thread, &pvRet); } while (rc == EINTR); if (rc) return RTErrConvertFromErrno(rc); return (int)(uintptr_t)pvRet; } return RTErrConvertFromErrno(rc); } static void rtSchedDumpPriority(void) { #ifdef THREAD_LOGGING Log(("Priority: g_fCanRaisePriority=%RTbool g_fCanRestorePriority=%RTbool g_fScrewedUpMaxPriorityLimitInheritance=%RTbool\n", g_fCanRaisePriority, g_fCanRestorePriority, g_fScrewedUpMaxPriorityLimitInheritance)); Log(("Priority: g_iMaxPriority=%d g_iMinPriority=%d\n", g_iMaxPriority, g_iMinPriority)); Log(("Priority: enmPriority=%d \"%s\" iNice=%d iDelta=%d\n", g_pProcessPriority->enmPriority, g_pProcessPriority->pszName, g_pProcessPriority->iNice, g_pProcessPriority->iDelta)); Log(("Priority: %2d INFREQUENT_POLLER = %d\n", RTTHREADTYPE_INFREQUENT_POLLER, g_pProcessPriority->paTypes[RTTHREADTYPE_INFREQUENT_POLLER].iPriority)); Log(("Priority: %2d MAIN_HEAVY_WORKER = %d\n", RTTHREADTYPE_MAIN_HEAVY_WORKER, g_pProcessPriority->paTypes[RTTHREADTYPE_MAIN_HEAVY_WORKER].iPriority)); Log(("Priority: %2d EMULATION = %d\n", RTTHREADTYPE_EMULATION , g_pProcessPriority->paTypes[RTTHREADTYPE_EMULATION ].iPriority)); Log(("Priority: %2d DEFAULT = %d\n", RTTHREADTYPE_DEFAULT , g_pProcessPriority->paTypes[RTTHREADTYPE_DEFAULT ].iPriority)); Log(("Priority: %2d GUI = %d\n", RTTHREADTYPE_GUI , g_pProcessPriority->paTypes[RTTHREADTYPE_GUI ].iPriority)); Log(("Priority: %2d MAIN_WORKER = %d\n", RTTHREADTYPE_MAIN_WORKER , g_pProcessPriority->paTypes[RTTHREADTYPE_MAIN_WORKER ].iPriority)); Log(("Priority: %2d VRDP_IO = %d\n", RTTHREADTYPE_VRDP_IO , g_pProcessPriority->paTypes[RTTHREADTYPE_VRDP_IO ].iPriority)); Log(("Priority: %2d DEBUGGER = %d\n", RTTHREADTYPE_DEBUGGER , g_pProcessPriority->paTypes[RTTHREADTYPE_DEBUGGER ].iPriority)); Log(("Priority: %2d MSG_PUMP = %d\n", RTTHREADTYPE_MSG_PUMP , g_pProcessPriority->paTypes[RTTHREADTYPE_MSG_PUMP ].iPriority)); Log(("Priority: %2d IO = %d\n", RTTHREADTYPE_IO , g_pProcessPriority->paTypes[RTTHREADTYPE_IO ].iPriority)); Log(("Priority: %2d TIMER = %d\n", RTTHREADTYPE_TIMER , g_pProcessPriority->paTypes[RTTHREADTYPE_TIMER ].iPriority)); #endif } /** * This just checks if it can raise the priority after having been * created by a thread with a low priority. * * @returns zero on success, non-zero on failure. * @param pvUser The priority of the parent before it was lowered (cast to int). */ static void *rtSchedNativeSubProberThread(void *pvUser) { int iPriority = getpriority(PRIO_PROCESS, 0); Assert(iPriority == g_iMinPriority); if (setpriority(PRIO_PROCESS, 0, iPriority + 1)) return (void *)-1; if (setpriority(PRIO_PROCESS, 0, (int)(intptr_t)pvUser)) return (void *)-1; return (void *)0; } /** * The prober thread. * We don't want to mess with the priority of the calling thread. * * @remark This is pretty presumptive stuff, but if it works on Linux and * FreeBSD it does what I want. */ static void *rtSchedNativeProberThread(void *pvUser) { NOREF(pvUser); SAVEDPRIORITY SavedPriority; rtSchedNativeSave(&SavedPriority); /* * Check if we can get higher priority (typically only root can do this). * (Won't work right if our priority is -19 to start with, but what the heck.) * * We assume that the priority range is -19 to 19. Should probably find the right * define for this. */ int iStart = getpriority(PRIO_PROCESS, 0); int i = iStart; while (i-- > -20) if (setpriority(PRIO_PROCESS, 0, i)) break; g_iMaxPriority = getpriority(PRIO_PROCESS, 0); g_fCanRaisePriority = g_iMaxPriority < iStart; g_fCanRestorePriority = setpriority(PRIO_PROCESS, 0, iStart) == 0; /* * Check if we temporarily lower the thread priority. * Again, we assume we're not at the extreme end of the priority scale. */ iStart = getpriority(PRIO_PROCESS, 0); i = iStart; while (i++ < 19) if (setpriority(PRIO_PROCESS, 0, i)) break; g_iMinPriority = getpriority(PRIO_PROCESS, 0); if ( setpriority(PRIO_PROCESS, 0, iStart) || getpriority(PRIO_PROCESS, 0) != iStart) g_fCanRestorePriority = false; if (g_iMinPriority == g_iMaxPriority) g_fCanRestorePriority = g_fCanRaisePriority = false; /* * Check what happens to child threads when the parent lowers the * priority when it's being created. */ iStart = getpriority(PRIO_PROCESS, 0); g_fScrewedUpMaxPriorityLimitInheritance = true; if ( g_fCanRestorePriority && !setpriority(PRIO_PROCESS, 0, g_iMinPriority) && iStart != g_iMinPriority) { if (rtSchedRunThread(rtSchedNativeSubProberThread, (void *)(intptr_t)iStart) == 0) g_fScrewedUpMaxPriorityLimitInheritance = false; } /* done */ rtSchedNativeRestore(&SavedPriority); return (void *)VINF_SUCCESS; } /** * Calculate the scheduling properties for all the threads in the default * process priority, assuming the current thread have the type enmType. * * @returns iprt status code. * @param enmType The thread type to be assumed for the current thread. */ DECLHIDDEN(int) rtSchedNativeCalcDefaultPriority(RTTHREADTYPE enmType) { Assert(enmType > RTTHREADTYPE_INVALID && enmType < RTTHREADTYPE_END); /* * First figure out what's we're allowed to do in this process. */ if (!g_fInitialized) { int iPriority = getpriority(PRIO_PROCESS, 0); #ifdef RLIMIT_RTPRIO /** @todo */ #endif int rc = rtSchedRunThread(rtSchedNativeProberThread, NULL); if (RT_FAILURE(rc)) return rc; Assert(getpriority(PRIO_PROCESS, 0) == iPriority); NOREF(iPriority); g_fInitialized = true; } /* * Select the right priority type table and update the default * process priority structure. */ if (g_fCanRaisePriority && g_fCanRestorePriority && !g_fScrewedUpMaxPriorityLimitInheritance) g_aDefaultPriority.paTypes = &g_aTypesLinuxFree[0]; else if (!g_fCanRaisePriority && g_fCanRestorePriority && !g_fScrewedUpMaxPriorityLimitInheritance) g_aDefaultPriority.paTypes = &g_aTypesLinuxRestricted[0]; else g_aDefaultPriority.paTypes = &g_aTypesLinuxFlat[0]; Assert(enmType == g_aDefaultPriority.paTypes[enmType].enmType); int iPriority = getpriority(PRIO_PROCESS, 0 /* current process */); g_aDefaultPriority.iNice = iPriority - g_aDefaultPriority.paTypes[enmType].iPriority; g_aDefaultPriority.iDelta = g_aDefaultPriority.iNice; rtSchedDumpPriority(); return VINF_SUCCESS; } /** * The process priority validator thread. * (We don't want to mess with the priority of the calling thread.) */ static void *rtSchedNativeValidatorThread(void *pvUser) { const PROCPRIORITY *pCfg = (const PROCPRIORITY *)pvUser; SAVEDPRIORITY SavedPriority; rtSchedNativeSave(&SavedPriority); /* * Try out the priorities from the top and down. */ int rc = VINF_SUCCESS; int i = RTTHREADTYPE_END; while (--i > RTTHREADTYPE_INVALID) { int iPriority = pCfg->paTypes[i].iPriority + pCfg->iDelta; if (setpriority(PRIO_PROCESS, 0, iPriority)) { rc = RTErrConvertFromErrno(errno); break; } } /* done */ rtSchedNativeRestore(&SavedPriority); return (void *)(intptr_t)rc; } /** * Validates and sets the process priority. * * This will check that all rtThreadNativeSetPriority() will success for all the * thread types when applied to the current thread. * * @returns iprt status code. * @param enmPriority The priority to validate and set. */ DECLHIDDEN(int) rtProcNativeSetPriority(RTPROCPRIORITY enmPriority) { Assert(enmPriority > RTPROCPRIORITY_INVALID && enmPriority < RTPROCPRIORITY_LAST); int rc = VINF_SUCCESS; if (enmPriority == RTPROCPRIORITY_DEFAULT) g_pProcessPriority = &g_aDefaultPriority; else { /* * Find a configuration which matches and can be applied. */ rc = VERR_FILE_NOT_FOUND; for (unsigned i = 0; i < RT_ELEMENTS(g_aUnixConfigs); i++) { if (g_aUnixConfigs[i].enmPriority == enmPriority) { int iPriority = getpriority(PRIO_PROCESS, 0); int rc3 = rtSchedRunThread(rtSchedNativeValidatorThread, (void *)&g_aUnixConfigs[i]); Assert(getpriority(PRIO_PROCESS, 0) == iPriority); NOREF(iPriority); if (RT_SUCCESS(rc3)) { g_pProcessPriority = &g_aUnixConfigs[i]; rc = VINF_SUCCESS; break; } if (rc == VERR_FILE_NOT_FOUND) rc = rc3; } } } #ifdef THREAD_LOGGING LogFlow(("rtProcNativeSetPriority: returns %Rrc enmPriority=%d\n", rc, enmPriority)); rtSchedDumpPriority(); #endif return rc; } /** * Sets the priority of the thread according to the thread type * and current process priority. * * The RTTHREADINT::enmType member has not yet been updated and will be updated by * the caller on a successful return. * * @returns iprt status code. * @param pThread The thread in question. * @param enmType The thread type. */ DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType) { /* sanity */ Assert(enmType > RTTHREADTYPE_INVALID && enmType < RTTHREADTYPE_END); Assert(enmType == g_pProcessPriority->paTypes[enmType].enmType); Assert((pthread_t)pThread->Core.Key == pthread_self()); RT_NOREF_PV(pThread); /* * Calculate the thread priority and apply it. */ int rc = VINF_SUCCESS; int iPriority = g_pProcessPriority->paTypes[enmType].iPriority + g_pProcessPriority->iDelta; if (!setpriority(PRIO_PROCESS, 0, iPriority)) { AssertMsg(iPriority == getpriority(PRIO_PROCESS, 0), ("iPriority=%d getpriority()=%d\n", iPriority, getpriority(PRIO_PROCESS, 0))); #ifdef THREAD_LOGGING Log(("rtThreadNativeSetPriority: Thread=%p enmType=%d iPriority=%d pid=%d\n", pThread->Core.Key, enmType, iPriority, getpid())); #endif } else { rc = RTErrConvertFromErrno(errno); AssertMsgFailed(("setpriority(,, %d) -> errno=%d rc=%Rrc\n", iPriority, errno, rc)); rc = VINF_SUCCESS; //non-fatal for now. } return rc; }