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Kernel: When a lock is busy, donate remaining process ticks to lock holder.

Since we know who's holding the lock, and we're gonna have to yield anyway,
we can just ask the scheduler to donate any remaining ticks to that process.
This commit is contained in:
Andreas Kling 2019-02-07 11:12:23 +01:00
parent 4df92709c8
commit 5582a0a254
15 changed files with 51 additions and 15 deletions

View file

@ -27,16 +27,19 @@ static inline dword CAS(volatile dword* mem, dword newval, dword oldval)
class Lock { class Lock {
public: public:
Lock() { } Lock(const char* name = nullptr) : m_name(name) { }
~Lock() { } ~Lock() { }
void lock(); void lock();
void unlock(); void unlock();
const char* name() const { return m_name; }
private: private:
volatile dword m_lock { 0 }; volatile dword m_lock { 0 };
dword m_level { 0 }; dword m_level { 0 };
Process* m_holder { nullptr }; Process* m_holder { nullptr };
const char* m_name { nullptr };
}; };
class Locker { class Locker {
@ -65,7 +68,7 @@ inline void Lock::lock()
} }
m_lock = 0; m_lock = 0;
} }
Scheduler::yield(); Scheduler::donate_to(m_holder, m_name);
} }
} }
@ -86,7 +89,7 @@ inline void Lock::unlock()
m_lock = 0; m_lock = 0;
return; return;
} }
Scheduler::yield(); Scheduler::donate_to(m_holder, m_name);
} }
} }

View file

@ -9,6 +9,7 @@ public:
DoubleBuffer() DoubleBuffer()
: m_write_buffer(&m_buffer1) : m_write_buffer(&m_buffer1)
, m_read_buffer(&m_buffer2) , m_read_buffer(&m_buffer2)
, m_lock("DoubleBuffer")
{ {
} }

View file

@ -85,7 +85,8 @@ FS::DirectoryEntry::DirectoryEntry(const char* n, size_t nl, InodeIdentifier i,
} }
Inode::Inode(FS& fs, unsigned index) Inode::Inode(FS& fs, unsigned index)
: m_fs(fs) : m_lock("Inode")
, m_fs(fs)
, m_index(index) , m_index(index)
{ {
all_inodes().set(this); all_inodes().set(this);

View file

@ -39,6 +39,7 @@ RetainPtr<IDEDiskDevice> IDEDiskDevice::create()
IDEDiskDevice::IDEDiskDevice() IDEDiskDevice::IDEDiskDevice()
: IRQHandler(IRQ_FIXED_DISK) : IRQHandler(IRQ_FIXED_DISK)
, m_lock("IDEDiskDevice")
{ {
initialize(); initialize();
} }

View file

@ -14,6 +14,7 @@ PTYMultiplexer& PTYMultiplexer::the()
PTYMultiplexer::PTYMultiplexer() PTYMultiplexer::PTYMultiplexer()
: CharacterDevice(5, 2) : CharacterDevice(5, 2)
, m_lock("PTYMultiplexer")
{ {
s_the = this; s_the = this;
m_freelist.ensure_capacity(s_max_pty_pairs); m_freelist.ensure_capacity(s_max_pty_pairs);

View file

@ -496,7 +496,7 @@ ByteBuffer procfs$all(InodeIdentifier)
auto processes = Process::all_processes(); auto processes = Process::all_processes();
StringBuilder builder; StringBuilder builder;
auto build_process_line = [&builder] (Process* process) { auto build_process_line = [&builder] (Process* process) {
builder.appendf("%u,%u,%u,%u,%u,%u,%u,%s,%u,%u,%s,%s,%u,%u,%u,%u\n", builder.appendf("%u,%u,%u,%u,%u,%u,%u,%s,%u,%u,%s,%s,%u,%u,%u,%u,%u\n",
process->pid(), process->pid(),
process->times_scheduled(), process->times_scheduled(),
process->tty() ? process->tty()->pgid() : 0, process->tty() ? process->tty()->pgid() : 0,
@ -512,7 +512,8 @@ ByteBuffer procfs$all(InodeIdentifier)
process->amount_virtual(), process->amount_virtual(),
process->amount_resident(), process->amount_resident(),
process->amount_shared(), process->amount_shared(),
process->amount_in_bitmaps() process->amount_in_bitmaps(),
process->ticks()
); );
}; };
build_process_line(Scheduler::colonel()); build_process_line(Scheduler::colonel());

View file

@ -2192,3 +2192,13 @@ void Process::finalize_dying_processes()
for (auto* process : dying_processes) for (auto* process : dying_processes)
process->finalize(); process->finalize();
} }
bool Process::tick()
{
++m_ticks;
if (tss().cs & 3)
++m_ticks_in_user;
else
++m_ticks_in_kernel;
return --m_ticks_left;
}

View file

@ -131,8 +131,9 @@ public:
template<typename Callback> static void for_each_living(Callback); template<typename Callback> static void for_each_living(Callback);
template<typename Callback> void for_each_child(Callback); template<typename Callback> void for_each_child(Callback);
bool tick() { ++m_ticks; return --m_ticks_left; } bool tick();
void set_ticks_left(dword t) { m_ticks_left = t; } void set_ticks_left(dword t) { m_ticks_left = t; }
dword ticks_left() const { return m_ticks_left; }
void set_selector(word s) { m_far_ptr.selector = s; } void set_selector(word s) { m_far_ptr.selector = s; }
void set_state(State s) { m_state = s; } void set_state(State s) { m_state = s; }

View file

@ -192,6 +192,24 @@ bool Scheduler::pick_next()
} }
} }
bool Scheduler::donate_to(Process* beneficiary, const char* reason)
{
(void)reason;
unsigned ticks_left = current->ticks_left();
if (!beneficiary || beneficiary->state() != Process::Runnable || ticks_left <= 1) {
return yield();
}
unsigned ticks_to_donate = ticks_left - 1;
#ifdef SCHEDULER_DEBUG
dbgprintf("%s(%u) donating %u ticks to %s(%u), reason=%s\n", current->name().characters(), current->pid(), ticks_to_donate, beneficiary->name().characters(), beneficiary->pid(), reason);
#endif
context_switch(*beneficiary);
beneficiary->set_ticks_left(ticks_to_donate);
switch_now();
return 0;
}
bool Scheduler::yield() bool Scheduler::yield()
{ {
InterruptDisabler disabler; InterruptDisabler disabler;
@ -229,12 +247,6 @@ bool Scheduler::context_switch(Process& process)
process.set_ticks_left(time_slice); process.set_ticks_left(time_slice);
process.did_schedule(); process.did_schedule();
if (process.tss().cs & 3) {
++process.m_ticks_in_user;
} else {
++process.m_ticks_in_kernel;
}
if (current == &process) if (current == &process)
return false; return false;

View file

@ -17,6 +17,7 @@ public:
static void pick_next_and_switch_now(); static void pick_next_and_switch_now();
static void switch_now(); static void switch_now();
static bool yield(); static bool yield();
static bool donate_to(Process*, const char* reason);
static bool context_switch(Process&); static bool context_switch(Process&);
static void prepare_to_modify_tss(Process&); static void prepare_to_modify_tss(Process&);
static Process* colonel(); static Process* colonel();

View file

@ -11,6 +11,7 @@ RetainPtr<SynthFS> SynthFS::create()
} }
SynthFS::SynthFS() SynthFS::SynthFS()
: m_lock("SynthFS")
{ {
} }

View file

@ -43,7 +43,7 @@ static Snapshot get_snapshot()
if (!ptr) if (!ptr)
break; break;
auto parts = String(buf, Chomp).split(','); auto parts = String(buf, Chomp).split(',');
if (parts.size() < 16) if (parts.size() < 17)
break; break;
bool ok; bool ok;
pid_t pid = parts[0].to_uint(ok); pid_t pid = parts[0].to_uint(ok);

View file

@ -13,6 +13,7 @@
static WSMessageLoop* s_the; static WSMessageLoop* s_the;
WSMessageLoop::WSMessageLoop() WSMessageLoop::WSMessageLoop()
: m_lock("WSMessageLoop")
{ {
if (!s_the) if (!s_the)
s_the = this; s_the = this;

View file

@ -5,7 +5,8 @@
#include "Process.h" #include "Process.h"
WSWindow::WSWindow(Process& process, int window_id) WSWindow::WSWindow(Process& process, int window_id)
: m_process(&process) : m_lock("WSWindow")
, m_process(&process)
, m_window_id(window_id) , m_window_id(window_id)
, m_pid(process.pid()) , m_pid(process.pid())
{ {

View file

@ -130,6 +130,7 @@ void WSWindowManager::flip_buffers()
WSWindowManager::WSWindowManager() WSWindowManager::WSWindowManager()
: m_screen(WSScreen::the()) : m_screen(WSScreen::the())
, m_screen_rect(m_screen.rect()) , m_screen_rect(m_screen.rect())
, m_lock("WSWindowManager")
{ {
#ifndef DEBUG_COUNTERS #ifndef DEBUG_COUNTERS
(void)m_compose_count; (void)m_compose_count;