[ros-diffs] [reactos] 01/14: [NTOS:Mm] Replace YieldProcessor() with KeDelayExecutionThread()

[Timo Kreuzer]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=477792856e42be09b12fd…

commit 477792856e42be09b12fd3e3ce557657c6cc63c2
Author:     Timo Kreuzer <timo.kreuzer(a)reactos.org>
AuthorDate: Sat Apr 1 19:18:45 2023 +0300
Commit:     Timo Kreuzer <timo.kreuzer(a)reactos.org>
CommitDate: Sat Jul 29 14:00:44 2023 +0300

    [NTOS:Mm] Replace YieldProcessor() with KeDelayExecutionThread()
    
    These are used in the paging path, when the page is currently in the process of being
read from or written to the disk. While YieldProcessor() provides the chance to switch
context to the other paging thread, it only does so, once the current thread's quantum
has expired. On a single CPU system this effectively leads to busy waiting for the rest of
the quantum. On SMP systems this could succeed earlier, thus reducing latency, but it
would still contribute to high CPU usage, while wait [...]
    Using KeDelayExecutionThread() will instantly allow another thread to run, providing
enough time to complete the IO operation.
---
 ntoskrnl/mm/section.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/ntoskrnl/mm/section.c b/ntoskrnl/mm/section.c
index 49c0e0e8f4f..33584a02230 100644
--- a/ntoskrnl/mm/section.c
+++ b/ntoskrnl/mm/section.c
@@ -1477,7 +1477,7 @@ MmAlterViewAttributes(PMMSUPPORT AddressSpace,
                     break;
                 MmUnlockSectionSegment(Segment);
                 MmUnlockAddressSpace(AddressSpace);
-                YieldProcessor();
+                KeDelayExecutionThread(KernelMode, FALSE, &TinyTime);
                 MmLockAddressSpace(AddressSpace);
                 MmLockSectionSegment(Segment);
             }
@@ -1608,7 +1608,7 @@ MmNotPresentFaultSectionView(PMMSUPPORT AddressSpace,
         if (SwapEntry == MM_WAIT_ENTRY)
         {
             MmUnlockAddressSpace(AddressSpace);
-            YieldProcessor();
+            KeDelayExecutionThread(KernelMode, FALSE, &TinyTime);
             MmLockAddressSpace(AddressSpace);
             return STATUS_MM_RESTART_OPERATION;
         }
@@ -1789,7 +1789,7 @@ MmNotPresentFaultSectionView(PMMSUPPORT AddressSpace,
         {
             MmUnlockSectionSegment(Segment);
             MmUnlockAddressSpace(AddressSpace);
-            YieldProcessor();
+            KeDelayExecutionThread(KernelMode, FALSE, &TinyTime);
             MmLockAddressSpace(AddressSpace);
             return STATUS_MM_RESTART_OPERATION;
         }
@@ -3442,7 +3442,7 @@ MmFreeSectionPage(PVOID Context, MEMORY_AREA* MemoryArea, PVOID
Address,
         MmUnlockSectionSegment(Segment);
         MmUnlockAddressSpace(AddressSpace);
 
-        YieldProcessor();
+        KeDelayExecutionThread(KernelMode, FALSE, &TinyTime);
 
         MmLockAddressSpace(AddressSpace);
         MmLockSectionSegment(Segment);
@@ -5202,7 +5202,7 @@ MmMakePagesDirty(
         {
             MmUnlockSectionSegment(Segment);
             MmUnlockAddressSpace(AddressSpace);
-            YieldProcessor();
+            KeDelayExecutionThread(KernelMode, FALSE, &TinyTime);
             MmLockAddressSpace(AddressSpace);
             MmLockSectionSegment(Segment);
             Entry = MmGetPageEntrySectionSegment(Segment, &SegmentOffset);