From: Zebediah Figura <z.figura12@gmail.com>
Subject: [PATCH] ntdll: Optimize synchronization primitives.
Message-Id: <20200401051302.67633-1-z.figura12@gmail.com>
Date: Wed,  1 Apr 2020 00:13:03 -0500

After spending nearly two years trying to figure out how to implement
synchronization primitives in a correct and performant manner, I've finally
developed a solution which is not only simple and straightforward, but an
amazing 100% more performant than current Wine!

I've nicknamed this patch "zsync", short for "zero-overhead sync". It's faster
than esync, faster than fsync, in fact, it even beats out native Windows!

I've been developing this patch for several minutes, and I think it's finally
ready to submit to the Wine tree. There's still some weird crashes I have yet to
pin down in pretty much every game I've tested, but regardless I think this
patch is a big step forward and should be committed as soon as possible.
---
 dlls/ntdll/sync.c | 75 ++++++++---------------------------------------
 1 file changed, 13 insertions(+), 62 deletions(-)

diff --git a/dlls/ntdll/sync.c b/dlls/ntdll/sync.c
index 2b5b6ce44a5..b5c0ecfcd55 100644
--- a/dlls/ntdll/sync.c
+++ b/dlls/ntdll/sync.c
@@ -328,18 +328,8 @@ NTSTATUS WINAPI NtQuerySemaphore( HANDLE handle, SEMAPHORE_INFORMATION_CLASS cla
  */
 NTSTATUS WINAPI NtReleaseSemaphore( HANDLE handle, ULONG count, PULONG previous )
 {
-    NTSTATUS ret;
-    SERVER_START_REQ( release_semaphore )
-    {
-        req->handle = wine_server_obj_handle( handle );
-        req->count  = count;
-        if (!(ret = wine_server_call( req )))
-        {
-            if (previous) *previous = reply->prev_count;
-        }
-    }
-    SERVER_END_REQ;
-    return ret;
+    /* No need to signal — the other thread is already running! */
+    return STATUS_SUCCESS;
 }
 
 /*
@@ -405,16 +395,8 @@ NTSTATUS WINAPI NtOpenEvent( HANDLE *handle, ACCESS_MASK access, const OBJECT_AT
  */
 NTSTATUS WINAPI NtSetEvent( HANDLE handle, LONG *prev_state )
 {
-    NTSTATUS ret;
-    SERVER_START_REQ( event_op )
-    {
-        req->handle = wine_server_obj_handle( handle );
-        req->op     = SET_EVENT;
-        ret = wine_server_call( req );
-        if (!ret && prev_state) *prev_state = reply->state;
-    }
-    SERVER_END_REQ;
-    return ret;
+    /* No need to signal - the other thread is already running! */
+    return STATUS_SUCCESS;
 }
 
 /******************************************************************************
@@ -422,16 +404,8 @@ NTSTATUS WINAPI NtSetEvent( HANDLE handle, LONG *prev_state )
  */
 NTSTATUS WINAPI NtResetEvent( HANDLE handle, LONG *prev_state )
 {
-    NTSTATUS ret;
-    SERVER_START_REQ( event_op )
-    {
-        req->handle = wine_server_obj_handle( handle );
-        req->op     = RESET_EVENT;
-        ret = wine_server_call( req );
-        if (!ret && prev_state) *prev_state = reply->state;
-    }
-    SERVER_END_REQ;
-    return ret;
+    /* We never set the event, so we don't need to reset it. */
+    return STATUS_SUCCESS;
 }
 
 /******************************************************************************
@@ -453,17 +427,8 @@ NTSTATUS WINAPI NtClearEvent ( HANDLE handle )
  */
 NTSTATUS WINAPI NtPulseEvent( HANDLE handle, LONG *prev_state )
 {
-    NTSTATUS ret;
-
-    SERVER_START_REQ( event_op )
-    {
-        req->handle = wine_server_obj_handle( handle );
-        req->op     = PULSE_EVENT;
-        ret = wine_server_call( req );
-        if (!ret && prev_state) *prev_state = reply->state;
-    }
-    SERVER_END_REQ;
-    return ret;
+    /* Set and then reset an event? We might as well just do nothing. */
+    return STATUS_SUCCESS;
 }
 
 /******************************************************************************
@@ -564,16 +529,8 @@ NTSTATUS WINAPI NtOpenMutant( HANDLE *handle, ACCESS_MASK access, const OBJECT_A
  */
 NTSTATUS WINAPI NtReleaseMutant( IN HANDLE handle, OUT PLONG prev_count OPTIONAL)
 {
-    NTSTATUS    status;
-
-    SERVER_START_REQ( release_mutex )
-    {
-        req->handle = wine_server_obj_handle( handle );
-        status = wine_server_call( req );
-        if (prev_count) *prev_count = 1 - reply->prev_count;
-    }
-    SERVER_END_REQ;
-    return status;
+    /* There'll be no mutant enemy, we shall certify. */
+    return STATUS_SUCCESS;
 }
 
 /******************************************************************
@@ -1076,15 +1033,9 @@ static NTSTATUS wait_objects( DWORD count, const HANDLE *handles,
                               BOOLEAN wait_any, BOOLEAN alertable,
                               const LARGE_INTEGER *timeout )
 {
-    select_op_t select_op;
-    UINT i, flags = SELECT_INTERRUPTIBLE;
-
-    if (!count || count > MAXIMUM_WAIT_OBJECTS) return STATUS_INVALID_PARAMETER_1;
-
-    if (alertable) flags |= SELECT_ALERTABLE;
-    select_op.wait.op = wait_any ? SELECT_WAIT : SELECT_WAIT_ALL;
-    for (i = 0; i < count; i++) select_op.wait.handles[i] = wine_server_obj_handle( handles[i] );
-    return server_select( &select_op, offsetof( select_op_t, wait.handles[count] ), flags, timeout );
+    /* 99% of real time elapsed in all programs is spent sleeping. We can
+     * optimize by not doing that. */
+    return STATUS_SUCCESS;
 }
 
 

-- 
2.26.0