[libc] Implement pthread_setschedparam and getschedparam (#205770)

Implemented the pthread_setschedparam and pthread_getschedparam
functions.

Added Linux syscall wrappers:
* sched_setscheduler
* sched_getscheduler
* sched_getparam

Updated the Thread class to support getting and setting scheduling
parameters.

Added integration tests to verify the implementation.

Assisted-by: Automated tooling, human reviewed.

libc/config/linux/aarch64/entrypoints.txt

@@ -1085,6 +1085,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.pthread.pthread_equal
     libc.src.pthread.pthread_exit
     libc.src.pthread.pthread_getname_np
+    libc.src.pthread.pthread_getschedparam
     libc.src.pthread.pthread_getspecific
     libc.src.pthread.pthread_getthreadid_np
     libc.src.pthread.pthread_getunique_np
@@ -1129,6 +1130,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.pthread.pthread_spin_unlock
     libc.src.pthread.pthread_self
     libc.src.pthread.pthread_setname_np
+    libc.src.pthread.pthread_setschedparam
     libc.src.pthread.pthread_setspecific
 
     # sched.h entrypoints

libc/config/linux/riscv/entrypoints.txt

@@ -1279,6 +1279,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.pthread.pthread_equal
     libc.src.pthread.pthread_exit
     libc.src.pthread.pthread_getname_np
+    libc.src.pthread.pthread_getschedparam
     libc.src.pthread.pthread_getspecific
     libc.src.pthread.pthread_getthreadid_np
     libc.src.pthread.pthread_getunique_np
@@ -1326,6 +1327,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.pthread.pthread_spin_unlock
     libc.src.pthread.pthread_self
     libc.src.pthread.pthread_setname_np
+    libc.src.pthread.pthread_setschedparam
     libc.src.pthread.pthread_setspecific
 
     # sched.h entrypoints

libc/config/linux/x86_64/entrypoints.txt

@@ -1284,6 +1284,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.pthread.pthread_equal
     libc.src.pthread.pthread_exit
     libc.src.pthread.pthread_getname_np
+    libc.src.pthread.pthread_getschedparam
     libc.src.pthread.pthread_getspecific
     libc.src.pthread.pthread_getthreadid_np
     libc.src.pthread.pthread_getunique_np
@@ -1331,6 +1332,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.pthread.pthread_spin_unlock
     libc.src.pthread.pthread_self
     libc.src.pthread.pthread_setname_np
+    libc.src.pthread.pthread_setschedparam
     libc.src.pthread.pthread_setspecific
 
     # sched.h entrypoints

libc/hdr/types/CMakeLists.txt

@@ -333,6 +333,15 @@ add_proxy_header_library(
     libc.include.llvm-libc-types.pthread_barrierattr_t
 )
 
+add_proxy_header_library(
+  pthread_t
+  HDRS
+    pthread_t.h
+  FULL_BUILD_DEPENDS
+    libc.include.llvm-libc-types.pthread_t
+    libc.include.pthread
+)
+
 add_proxy_header_library(
   atexithandler_t
   HDRS

libc/hdr/types/pthread_t.h

@@ -0,0 +1,22 @@
+//===-- Proxy for pthread_t -----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_HDR_TYPES_PTHREAD_T_H
+#define LLVM_LIBC_HDR_TYPES_PTHREAD_T_H
+
+#ifdef LIBC_FULL_BUILD
+
+#include "include/llvm-libc-types/pthread_t.h"
+
+#else // Overlay mode
+
+#include <pthread.h>
+
+#endif // LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_TYPES_PTHREAD_T_H

libc/include/pthread.yaml

@@ -232,6 +232,12 @@ functions:
       - type: pthread_t
       - type: char *
       - type: size_t
+  - name: pthread_getschedparam
+    return_type: int
+    arguments:
+      - type: pthread_t
+      - type: int *__restrict
+      - type: struct sched_param *__restrict
   - name: pthread_getspecific
     return_type: void *
     arguments:
@@ -422,6 +428,12 @@ functions:
     arguments:
       - type: pthread_t
       - type: const char *
+  - name: pthread_setschedparam
+    return_type: int
+    arguments:
+      - type: pthread_t
+      - type: int
+      - type: const struct sched_param *
   - name: pthread_setspecific
     return_type: int
     arguments:

libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt

@@ -40,6 +40,47 @@ add_header_library(
     libc.include.sys_syscall
 )
 
+add_header_library(
+  sched_setscheduler
+  HDRS
+    sched_setscheduler.h
+  DEPENDS
+    libc.hdr.types.pid_t
+    libc.hdr.types.struct_sched_param
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  sched_getscheduler
+  HDRS
+    sched_getscheduler.h
+  DEPENDS
+    libc.hdr.types.pid_t
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  sched_getparam
+  HDRS
+    sched_getparam.h
+  DEPENDS
+    libc.hdr.types.pid_t
+    libc.hdr.types.struct_sched_param
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.include.sys_syscall
+)
+
 add_header_library(
   close
   HDRS

libc/src/__support/OSUtil/linux/syscall_wrappers/sched_getparam.h

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for sched_getparam syscall wrapper.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_GETPARAM_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_GETPARAM_H
+
+#include "hdr/types/pid_t.h"
+#include "hdr/types/struct_sched_param.h"
+#include "src/__support/OSUtil/linux/syscall.h" // syscall_checked
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE ErrorOr<int> sched_getparam(pid_t tid, struct sched_param *param) {
+  return syscall_checked<int>(SYS_sched_getparam, tid, param);
+}
+
+} // namespace linux_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_GETPARAM_H

libc/src/__support/OSUtil/linux/syscall_wrappers/sched_getscheduler.h

@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for sched_getscheduler syscall wrapper.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_GETSCHEDULER_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_GETSCHEDULER_H
+
+#include "hdr/types/pid_t.h"
+#include "src/__support/OSUtil/linux/syscall.h" // syscall_checked
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE ErrorOr<int> sched_getscheduler(pid_t tid) {
+  return syscall_checked<int>(SYS_sched_getscheduler, tid);
+}
+
+} // namespace linux_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_GETSCHEDULER_H

libc/src/__support/OSUtil/linux/syscall_wrappers/sched_setscheduler.h

@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for sched_setscheduler syscall wrapper.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_SETSCHEDULER_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_SETSCHEDULER_H
+
+#include "hdr/types/pid_t.h"
+#include "hdr/types/struct_sched_param.h"
+#include "src/__support/OSUtil/linux/syscall.h" // syscall_checked
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE ErrorOr<int> sched_setscheduler(pid_t tid, int policy,
+                                            const struct sched_param *param) {
+  return syscall_checked<int>(SYS_sched_setscheduler, tid, policy, param);
+}
+
+} // namespace linux_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SCHED_SETSCHEDULER_H

libc/src/__support/threads/CMakeLists.txt

@@ -112,7 +112,9 @@ add_header_library(
     thread.h
   DEPENDS
     libc.hdr.stdint_proxy
+    libc.hdr.types.struct_sched_param
     libc.src.__support.common
+    libc.src.__support.error_or
     libc.src.__support.CPP.atomic
     libc.src.__support.CPP.optional
     libc.src.__support.CPP.string_view

libc/src/__support/threads/linux/CMakeLists.txt

@@ -47,6 +47,9 @@ add_object_library(
     libc.src.__support.OSUtil.linux.syscall_wrappers.munmap
     libc.src.__support.OSUtil.linux.syscall_wrappers.open
     libc.src.__support.OSUtil.linux.syscall_wrappers.read
+    libc.src.__support.OSUtil.linux.syscall_wrappers.sched_getparam
+    libc.src.__support.OSUtil.linux.syscall_wrappers.sched_getscheduler
+    libc.src.__support.OSUtil.linux.syscall_wrappers.sched_setscheduler
     libc.src.__support.OSUtil.linux.syscall_wrappers.write
     libc.src.__support.threads.thread_common
   COMPILE_OPTIONS

libc/src/__support/threads/linux/thread.cpp

@@ -17,6 +17,9 @@
 #include "src/__support/OSUtil/linux/syscall_wrappers/munmap.h"
 #include "src/__support/OSUtil/linux/syscall_wrappers/open.h"
 #include "src/__support/OSUtil/linux/syscall_wrappers/read.h"
+#include "src/__support/OSUtil/linux/syscall_wrappers/sched_getparam.h"
+#include "src/__support/OSUtil/linux/syscall_wrappers/sched_getscheduler.h"
+#include "src/__support/OSUtil/linux/syscall_wrappers/sched_setscheduler.h"
 #include "src/__support/OSUtil/linux/syscall_wrappers/write.h"
 #include "src/__support/OSUtil/syscall.h" // For syscall functions.
 #include "src/__support/common.h"
@@ -490,6 +493,27 @@ int Thread::get_name(cpp::StringStream &name) const {
   return 0;
 }
 
+int Thread::setschedparam(SchedParameters params) {
+  auto result = linux_syscalls::sched_setscheduler(attrib->tid, params.policy,
+                                                   &params.param);
+  if (!result.has_value())
+    return result.error();
+  return 0;
+}
+
+ErrorOr<SchedParameters> Thread::getschedparam() const {
+  auto pol_result = linux_syscalls::sched_getscheduler(attrib->tid);
+  if (!pol_result.has_value())
+    return Error(pol_result.error());
+
+  struct sched_param param;
+  auto param_result = linux_syscalls::sched_getparam(attrib->tid, &param);
+  if (!param_result.has_value())
+    return Error(param_result.error());
+
+  return SchedParameters{pol_result.value(), param};
+}
+
 void thread_exit(ThreadReturnValue retval, ThreadStyle style) {
   auto attrib = self.attrib;
 

libc/src/__support/threads/thread.h

@@ -10,10 +10,12 @@
 #define LLVM_LIBC_SRC___SUPPORT_THREADS_THREAD_H
 
 #include "hdr/stdint_proxy.h"
+#include "hdr/types/struct_sched_param.h"
 #include "src/__support/CPP/atomic.h"
 #include "src/__support/CPP/optional.h"
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/CPP/stringstream.h"
+#include "src/__support/error_or.h"
 #include "src/__support/macros/attributes.h"
 #include "src/__support/macros/config.h"
 #include "src/__support/macros/properties/architectures.h"
@@ -25,6 +27,11 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
+struct SchedParameters {
+  int policy;
+  struct sched_param param;
+};
+
 using ThreadRunnerPosix = void *(void *);
 using ThreadRunnerStdc = int(void *);
 
@@ -230,6 +237,14 @@ struct Thread {
 
   // Return the name of the thread in |name|. Return the error number of error.
   int get_name(cpp::StringStream &name) const;
+
+  // Set the scheduling policy and parameters of the thread.
+  // Return 0 on success, or an error number on failure.
+  int setschedparam(SchedParameters params);
+
+  // Get the scheduling policy and parameters of the thread.
+  // Return SchedParameters on success, or an error number on failure.
+  ErrorOr<SchedParameters> getschedparam() const;
 };
 
 LIBC_INLINE_VAR LIBC_THREAD_LOCAL Thread self;

libc/src/pthread/CMakeLists.txt

@@ -941,3 +941,29 @@ add_entrypoint_object(
     libc.src.__support.threads.fork_callbacks
     libc.src.errno.errno
 )
+
+add_entrypoint_object(
+  pthread_setschedparam
+  SRCS
+    pthread_setschedparam.cpp
+  HDRS
+    pthread_setschedparam.h
+  DEPENDS
+    libc.hdr.types.pthread_t
+    libc.hdr.types.struct_sched_param
+    libc.src.__support.macros.null_check
+    libc.src.__support.threads.thread
+)
+
+add_entrypoint_object(
+  pthread_getschedparam
+  SRCS
+    pthread_getschedparam.cpp
+  HDRS
+    pthread_getschedparam.h
+  DEPENDS
+    libc.hdr.types.pthread_t
+    libc.hdr.types.struct_sched_param
+    libc.src.__support.macros.null_check
+    libc.src.__support.threads.thread
+)

libc/src/pthread/pthread_getschedparam.cpp

@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Linux implementation of the pthread_getschedparam function.
+///
+//===----------------------------------------------------------------------===//
+
+#include "pthread_getschedparam.h"
+
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
+#include "src/__support/threads/thread.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static_assert(sizeof(pthread_t) == sizeof(LIBC_NAMESPACE::Thread),
+              "Mismatch between pthread_t and internal Thread.");
+
+LLVM_LIBC_FUNCTION(int, pthread_getschedparam,
+                   (pthread_t th, int *__restrict policy,
+                    struct sched_param *__restrict param)) {
+  LIBC_CRASH_ON_NULLPTR(policy);
+  LIBC_CRASH_ON_NULLPTR(param);
+  auto *thread = reinterpret_cast<Thread *>(&th);
+  auto result = thread->getschedparam();
+  if (!result.has_value())
+    return result.error();
+
+  *policy = result.value().policy;
+  *param = result.value().param;
+  return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/pthread/pthread_getschedparam.h

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for pthread_getschedparam.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_GETSCHEDPARAM_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_GETSCHEDPARAM_H
+
+#include "hdr/types/pthread_t.h"
+#include "hdr/types/struct_sched_param.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_getschedparam(pthread_t thread, int *__restrict policy,
+                          struct sched_param *__restrict param);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_GETSCHEDPARAM_H

libc/src/pthread/pthread_setschedparam.cpp

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Linux implementation of the pthread_setschedparam function.
+///
+//===----------------------------------------------------------------------===//
+
+#include "pthread_setschedparam.h"
+
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
+#include "src/__support/threads/thread.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static_assert(sizeof(pthread_t) == sizeof(LIBC_NAMESPACE::Thread),
+              "Mismatch between pthread_t and internal Thread.");
+
+LLVM_LIBC_FUNCTION(int, pthread_setschedparam,
+                   (pthread_t th, int policy,
+                    const struct sched_param *param)) {
+  LIBC_CRASH_ON_NULLPTR(param);
+  auto *thread = reinterpret_cast<Thread *>(&th);
+  return thread->setschedparam({policy, *param});
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/pthread/pthread_setschedparam.h

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for pthread_setschedparam.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_SETSCHEDPARAM_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_SETSCHEDPARAM_H
+
+#include "hdr/types/pthread_t.h"
+#include "hdr/types/struct_sched_param.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_setschedparam(pthread_t thread, int policy,
+                          const struct sched_param *param);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_SETSCHEDPARAM_H

libc/test/integration/src/pthread/CMakeLists.txt

@@ -291,3 +291,21 @@ add_integration_test(
     libc.src.__support.CPP.array
     libc.src.__support.CPP.new
 )
+
+add_integration_test(
+  pthread_setschedparam_test
+  SUITE
+    libc-pthread-integration-tests
+  SRCS
+    pthread_setschedparam_test.cpp
+  DEPENDS
+    libc.hdr.errno_macros
+    libc.hdr.sched_macros
+    libc.hdr.types.struct_sched_param
+    libc.hdr.types.pthread_t
+    libc.src.pthread.pthread_create
+    libc.src.pthread.pthread_getschedparam
+    libc.src.pthread.pthread_join
+    libc.src.pthread.pthread_self
+    libc.src.pthread.pthread_setschedparam
+)

libc/test/integration/src/pthread/pthread_setschedparam_test.cpp

@@ -0,0 +1,92 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Integration tests for pthread_setschedparam and pthread_getschedparam.
+///
+//===----------------------------------------------------------------------===//
+
+#include "hdr/errno_macros.h"
+#include "hdr/sched_macros.h"
+#include "hdr/types/pthread_t.h"
+#include "hdr/types/struct_sched_param.h"
+#include "src/pthread/pthread_create.h"
+#include "src/pthread/pthread_getschedparam.h"
+#include "src/pthread/pthread_join.h"
+#include "src/pthread/pthread_self.h"
+#include "src/pthread/pthread_setschedparam.h"
+#include "test/IntegrationTest/test.h"
+
+static void *child_func(void *) { return nullptr; }
+
+TEST_MAIN() {
+  auto main_thread = LIBC_NAMESPACE::pthread_self();
+  struct sched_param param;
+  int policy;
+
+  // 1. Test getschedparam on self
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_getschedparam(main_thread, &policy, &param),
+            0);
+
+  // 2. Test setschedparam on self (Success)
+  param.sched_priority = 0;
+  ASSERT_EQ(
+      LIBC_NAMESPACE::pthread_setschedparam(main_thread, SCHED_OTHER, &param),
+      0);
+
+  // Verify it was set
+  int new_policy;
+  struct sched_param new_param;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_getschedparam(main_thread, &new_policy,
+                                                  &new_param),
+            0);
+  ASSERT_EQ(new_policy, SCHED_OTHER);
+  ASSERT_EQ(new_param.sched_priority, 0);
+
+  // 3. Test setschedparam on self (Failure - Invalid Policy)
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_setschedparam(main_thread, -1, &param),
+            EINVAL);
+
+  // 4. Test setschedparam on self (Failure - Invalid Priority for SCHED_OTHER)
+  param.sched_priority = 1; // Invalid for SCHED_OTHER
+  ASSERT_EQ(
+      LIBC_NAMESPACE::pthread_setschedparam(main_thread, SCHED_OTHER, &param),
+      EINVAL);
+  param.sched_priority = 0; // Reset
+
+  // 5. Test on Child Thread
+  pthread_t th;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_create(&th, nullptr, child_func, nullptr),
+            0);
+
+  // Get child's default sched param
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_getschedparam(th, &policy, &param), 0);
+
+  // Set child's sched param (Success)
+  param.sched_priority = 0;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_setschedparam(th, SCHED_OTHER, &param), 0);
+
+  // Verify child's sched param
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_getschedparam(th, &new_policy, &new_param),
+            0);
+  ASSERT_EQ(new_policy, SCHED_OTHER);
+  ASSERT_EQ(new_param.sched_priority, 0);
+
+  // Set child's sched param (Failure - Invalid Policy)
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_setschedparam(th, -1, &param), EINVAL);
+
+  // Set child's sched param (Failure - Invalid Priority)
+  param.sched_priority = 1;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_setschedparam(th, SCHED_OTHER, &param),
+            EINVAL);
+
+  void *retval;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_join(th, &retval), 0);
+
+  return 0;
+}