415 lines
9.0 KiB
C++
415 lines
9.0 KiB
C++
/* sched.cc: scheduler interface for Cygwin
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Written by Robert Collins <rbtcollins@hotmail.com>
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This file is part of Cygwin.
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This software is a copyrighted work licensed under the terms of the
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Cygwin license. Please consult the file "CYGWIN_LICENSE" for
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details. */
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#include "winsup.h"
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#include "miscfuncs.h"
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#include "cygerrno.h"
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#include "pinfo.h"
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#include "hires.h"
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/* for getpid */
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#include <unistd.h>
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#include <sys/param.h>
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#include "registry.h"
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/* Win32 priority to UNIX priority Mapping. */
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extern "C"
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{
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/* We support prio values from 1 to 32. This is marginally in line with Linux
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(1 - 99) and matches the POSIX requirement to support at least 32 priority
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values. */
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/* max priority for policy */
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int
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sched_get_priority_max (int policy)
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{
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switch (policy)
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{
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case SCHED_FIFO:
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case SCHED_RR:
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case SCHED_OTHER:
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return 32;
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}
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set_errno (EINVAL);
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return -1;
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}
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/* min priority for policy */
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int
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sched_get_priority_min (int policy)
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{
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switch (policy)
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{
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case SCHED_FIFO:
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case SCHED_RR:
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case SCHED_OTHER:
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return 1;
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}
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set_errno (EINVAL);
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return -1;
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}
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/* Check a scheduler parameter struct for valid settings */
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bool
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valid_sched_parameters (const struct sched_param *param)
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{
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return param->sched_priority >= 1 && param->sched_priority <= 32;
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}
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/* get sched params for process
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Note, we're never returning EPERM, always ESRCH. This is by design.
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Walking the pid values is a known hole in some OSes. */
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int
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sched_getparam (pid_t pid, struct sched_param *param)
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{
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pid_t localpid;
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if (!param || pid < 0)
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{
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set_errno (EINVAL);
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return -1;
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}
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localpid = pid ? pid : getpid ();
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DWORD pclass;
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HANDLE process;
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pinfo p (localpid);
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/* get the class */
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if (!p)
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{
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set_errno (ESRCH);
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return -1;
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}
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process = OpenProcess (PROCESS_QUERY_LIMITED_INFORMATION, FALSE,
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p->dwProcessId);
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if (!process)
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{
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set_errno (ESRCH);
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return -1;
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}
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pclass = GetPriorityClass (process);
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CloseHandle (process);
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if (!pclass)
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{
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set_errno (ESRCH);
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return -1;
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}
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/* calculate the unix priority. */
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switch (pclass)
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{
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case IDLE_PRIORITY_CLASS:
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param->sched_priority = 3;
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break;
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case BELOW_NORMAL_PRIORITY_CLASS:
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param->sched_priority = 9;
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break;
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case NORMAL_PRIORITY_CLASS:
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default:
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param->sched_priority = 15;
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break;
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case ABOVE_NORMAL_PRIORITY_CLASS:
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param->sched_priority = 21;
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break;
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case HIGH_PRIORITY_CLASS:
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param->sched_priority = 27;
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break;
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case REALTIME_PRIORITY_CLASS:
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param->sched_priority = 32;
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break;
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}
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return 0;
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}
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/* get the scheduler for pid
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All process's on WIN32 run with SCHED_FIFO. So we just give an answer.
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(WIN32 uses a multi queue FIFO).
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*/
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int
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sched_getscheduler (pid_t pid)
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{
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if (pid < 0)
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return ESRCH;
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else
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return SCHED_FIFO;
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}
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/* get the time quantum for pid */
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int
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sched_rr_get_interval (pid_t pid, struct timespec *interval)
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{
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static const char quantable[2][2][3] =
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{{{12, 24, 36}, { 6, 12, 18}},
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{{36, 36, 36}, {18, 18, 18}}};
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/* FIXME: Clocktickinterval can be 15 ms for multi-processor system. */
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static const int clocktickinterval = 10;
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static const int quantapertick = 3;
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HWND forwin;
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DWORD forprocid;
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DWORD vfindex, slindex, qindex, prisep;
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long nsec;
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forwin = GetForegroundWindow ();
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if (!forwin)
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GetWindowThreadProcessId (forwin, &forprocid);
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else
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forprocid = 0;
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reg_key reg (HKEY_LOCAL_MACHINE, KEY_READ, L"SYSTEM", L"CurrentControlSet",
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L"Control", L"PriorityControl", NULL);
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if (reg.error ())
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{
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set_errno (ESRCH);
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return -1;
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}
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prisep = reg.get_dword (L"Win32PrioritySeparation", 2);
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pinfo pi (pid ? pid : myself->pid);
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if (!pi)
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{
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set_errno (ESRCH);
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return -1;
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}
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if (pi->dwProcessId == forprocid)
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{
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qindex = prisep & 3;
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qindex = qindex == 3 ? 2 : qindex;
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}
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else
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qindex = 0;
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vfindex = ((prisep >> 2) & 3) % 3;
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if (vfindex == 0)
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vfindex = wincap.is_server () || (prisep & 3) == 0 ? 1 : 0;
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else
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vfindex -= 1;
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slindex = ((prisep >> 4) & 3) % 3;
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if (slindex == 0)
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slindex = wincap.is_server () ? 1 : 0;
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else
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slindex -= 1;
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nsec = quantable[vfindex][slindex][qindex] / quantapertick
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* clocktickinterval * (NSPERSEC / MSPERSEC);
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interval->tv_sec = nsec / NSPERSEC;
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interval->tv_nsec = nsec % NSPERSEC;
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return 0;
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}
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/* set the scheduling parameters */
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int
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sched_setparam (pid_t pid, const struct sched_param *param)
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{
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pid_t localpid;
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int pri;
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DWORD pclass;
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HANDLE process;
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if (!param || pid < 0)
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{
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set_errno (EINVAL);
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return -1;
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}
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if (!valid_sched_parameters (param))
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{
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set_errno (EINVAL);
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return -1;
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}
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pri = param->sched_priority;
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/* calculate our desired priority class. We only reserve a small area
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(31/32) for realtime priority. */
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if (pri <= 6)
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pclass = IDLE_PRIORITY_CLASS;
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else if (pri <= 12)
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pclass = BELOW_NORMAL_PRIORITY_CLASS;
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else if (pri <= 18)
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pclass = NORMAL_PRIORITY_CLASS;
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else if (pri <= 24)
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pclass = ABOVE_NORMAL_PRIORITY_CLASS;
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else if (pri <= 30)
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pclass = HIGH_PRIORITY_CLASS;
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else
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pclass = REALTIME_PRIORITY_CLASS;
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localpid = pid ? pid : getpid ();
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pinfo p (localpid);
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/* set the class */
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if (!p)
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{
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set_errno (ESRCH);
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return -1;
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}
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process = OpenProcess (PROCESS_SET_INFORMATION, FALSE, p->dwProcessId);
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if (!process)
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{
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set_errno (ESRCH);
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return -1;
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}
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if (!SetPriorityClass (process, pclass))
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{
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CloseHandle (process);
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set_errno (EPERM);
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return -1;
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}
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CloseHandle (process);
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return 0;
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}
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/* POSIX thread priorities loosely compare to Windows thread base priorities.
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Base priority is a function of process priority class and thread priority.
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https://msdn.microsoft.com/en-us/library/windows/desktop/ms685100%28v=vs.85%29.aspx
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Note 1:
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We deliberately handle the REALTIME prority class the same as the HIGH
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priority class. Realtime has it's own range from 16 to 31 so half the
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arena is reserved for REALTIME. The problem is that this isn't visible
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nor expected in the POSIX scenario. Therefore we hide this here and
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fold REALTIME into HIGH.
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Note 2:
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sched_get_thread_priority is only called internally and only for threads
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of the current process, with no good reason for the caller to fail.
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Therefore it never returns an error but a valid priority (base value
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equivalent to process priority class + THREAD_PRIORITY_NORMAL...
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Note 3:
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...multiplied by 2 to stretch the priorities over the entire range 1 - 32.
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*/
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static int
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sched_base_prio_from_win_prio_class (DWORD pclass)
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{
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int base;
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switch (pclass)
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{
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case IDLE_PRIORITY_CLASS:
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base = 4;
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break;
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case BELOW_NORMAL_PRIORITY_CLASS:
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base = 6;
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break;
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case NORMAL_PRIORITY_CLASS:
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default:
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base = 8;
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break;
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case ABOVE_NORMAL_PRIORITY_CLASS:
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base = 10;
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break;
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case HIGH_PRIORITY_CLASS:
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case REALTIME_PRIORITY_CLASS: /* See above note 1 */
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base = 13;
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break;
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}
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return base;
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}
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int
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sched_get_thread_priority (HANDLE thread)
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{
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int tprio;
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DWORD pclass;
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int priority;
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tprio = GetThreadPriority (thread);
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pclass = GetPriorityClass (GetCurrentProcess ());
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switch (tprio)
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{
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case THREAD_PRIORITY_ERROR_RETURN:
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priority = sched_base_prio_from_win_prio_class (pclass);
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break;
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case THREAD_PRIORITY_IDLE:
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priority = 1;
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break;
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case THREAD_PRIORITY_TIME_CRITICAL:
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priority = 15;
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break;
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default:
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priority = tprio + sched_base_prio_from_win_prio_class (pclass);
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break;
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}
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return priority << 1; /* See above note 3 */
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}
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int
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sched_set_thread_priority (HANDLE thread, int priority)
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{
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DWORD pclass;
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int tprio;
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pclass = GetPriorityClass (GetCurrentProcess ());
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if (!pclass)
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return EPERM;
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if (priority < 1 || priority > 32)
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return EINVAL;
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priority >>= 1; /* See above note 3 */
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if (priority < 1)
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priority = 1;
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else if (priority > 15)
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priority = 15;
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if (priority == 1)
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tprio = THREAD_PRIORITY_IDLE;
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else if (priority == 15)
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tprio = THREAD_PRIORITY_TIME_CRITICAL;
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else
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{
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tprio = priority - sched_base_prio_from_win_prio_class (pclass);
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/* Intermediate values only allowed in REALTIME_PRIORITY_CLASS. */
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if (pclass != REALTIME_PRIORITY_CLASS)
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{
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if (tprio < THREAD_PRIORITY_LOWEST)
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tprio = THREAD_PRIORITY_LOWEST;
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else if (tprio > THREAD_PRIORITY_HIGHEST)
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tprio = THREAD_PRIORITY_HIGHEST;
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}
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}
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if (!SetThreadPriority (thread, tprio))
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/* invalid handle, no access are the only expected errors. */
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return EPERM;
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return 0;
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}
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/* set the scheduler */
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int
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sched_setscheduler (pid_t pid, int policy,
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const struct sched_param *param)
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{
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/* on win32, you can't change the scheduler. Doh! */
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set_errno (ENOSYS);
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return -1;
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}
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/* yield the cpu */
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int
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sched_yield ()
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{
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SwitchToThread ();
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return 0;
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}
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}
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