Zhiyi Zhang : Revert "ntdll: Call usleep() instead of NtYieldExecution() in NtDelayExecution().".

[Alexandre Julliard]

Module: wine
Branch: master
Commit: fc3b2ebaf4d92a77025f5c532a2415ada8de69c3
URL:    https://gitlab.winehq.org/wine/wine/-/commit/fc3b2ebaf4d92a77025f5c532a2415a...

Author: Zhiyi Zhang <zzhang(a)codeweavers.com>
Date:   Wed Dec  7 10:17:25 2022 +0800

Revert "ntdll: Call usleep() instead of NtYieldExecution() in NtDelayExecution().".

Manual tests on Windows 10 show that calling Sleep(0) or NtDelayExecution() with zero timeout in a
loop do consume 100% of a CPU core, which is closer to the behavior of NtYieldExecution() than
usleep(0). usleep(0) gives up the remaining timeslices even if there are no other threads to switch
to, causing low utilization of CPU and performance issues.

The original patch is b1a79c6 and the idea is to use usleep(0) to avoid a thread taking 100% of a
CPU core for StarCraft 2 and Shadow of the Tomb Raider. However with wine-7.22, reverting the
usleep(0) patch causes no behavior changes. For Shadow of the Tomb Raider, the 100% CPU issue is
gone with or without the patch. For StarCraft 2, there is always a thread taking 100% CPU even with
the patch. After discussing with Matteo, we decided it's better to revert the patch.

Fix Mortal Kombat X performance drop during tower selection and Ragnarok Online bad performance.

This reverts commit e86b4015ff405d4c054b8a5bc855ee655e1a833c.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53327

---

 dlls/ntdll/unix/sync.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/ntdll/unix/sync.c b/dlls/ntdll/unix/sync.c
index 650e32a7d41..a0905963562 100644
--- a/dlls/ntdll/unix/sync.c
+++ b/dlls/ntdll/unix/sync.c
@@ -1494,7 +1494,7 @@ NTSTATUS WINAPI NtDelayExecution( BOOLEAN alertable, const LARGE_INTEGER *timeou
         }
 
         /* Note that we yield after establishing the desired timeout */
-        usleep(0);
+        NtYieldExecution();
         if (!when) return STATUS_SUCCESS;
 
         for (;;)