diff --git a/services/surfaceflinger/Scheduler/DispSync.cpp b/services/surfaceflinger/Scheduler/DispSync.cpp
index 172c418..b74b901 100644
--- a/services/surfaceflinger/Scheduler/DispSync.cpp
+++ b/services/surfaceflinger/Scheduler/DispSync.cpp
@@ -24,9 +24,9 @@
 
 #include <algorithm>
 
-#include <log/log.h>
+#include <android-base/stringprintf.h>
 #include <cutils/properties.h>
-#include <utils/String8.h>
+#include <log/log.h>
 #include <utils/Thread.h>
 #include <utils/Trace.h>
 
@@ -36,6 +36,7 @@
 #include "EventLog/EventLog.h"
 #include "SurfaceFlinger.h"
 
+using android::base::StringAppendF;
 using std::max;
 using std::min;
 
@@ -667,54 +668,56 @@
     }
 }
 
-void DispSync::dump(String8& result) const {
+void DispSync::dump(std::string& result) const {
     Mutex::Autolock lock(mMutex);
-    result.appendFormat("present fences are %s\n", mIgnorePresentFences ? "ignored" : "used");
-    result.appendFormat("mPeriod: %" PRId64 " ns (%.3f fps; skipCount=%d)\n", mPeriod,
-                        1000000000.0 / mPeriod, mRefreshSkipCount);
-    result.appendFormat("mPhase: %" PRId64 " ns\n", mPhase);
-    result.appendFormat("mError: %" PRId64 " ns (sqrt=%.1f)\n", mError, sqrt(mError));
-    result.appendFormat("mNumResyncSamplesSincePresent: %d (limit %d)\n",
-                        mNumResyncSamplesSincePresent, MAX_RESYNC_SAMPLES_WITHOUT_PRESENT);
-    result.appendFormat("mNumResyncSamples: %zd (max %d)\n", mNumResyncSamples, MAX_RESYNC_SAMPLES);
+    StringAppendF(&result, "present fences are %s\n", mIgnorePresentFences ? "ignored" : "used");
+    StringAppendF(&result, "mPeriod: %" PRId64 " ns (%.3f fps; skipCount=%d)\n", mPeriod,
+                  1000000000.0 / mPeriod, mRefreshSkipCount);
+    StringAppendF(&result, "mPhase: %" PRId64 " ns\n", mPhase);
+    StringAppendF(&result, "mError: %" PRId64 " ns (sqrt=%.1f)\n", mError, sqrt(mError));
+    StringAppendF(&result, "mNumResyncSamplesSincePresent: %d (limit %d)\n",
+                  mNumResyncSamplesSincePresent, MAX_RESYNC_SAMPLES_WITHOUT_PRESENT);
+    StringAppendF(&result, "mNumResyncSamples: %zd (max %d)\n", mNumResyncSamples,
+                  MAX_RESYNC_SAMPLES);
 
-    result.appendFormat("mResyncSamples:\n");
+    result.append("mResyncSamples:\n");
     nsecs_t previous = -1;
     for (size_t i = 0; i < mNumResyncSamples; i++) {
         size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;
         nsecs_t sampleTime = mResyncSamples[idx];
         if (i == 0) {
-            result.appendFormat("  %" PRId64 "\n", sampleTime);
+            StringAppendF(&result, "  %" PRId64 "\n", sampleTime);
         } else {
-            result.appendFormat("  %" PRId64 " (+%" PRId64 ")\n", sampleTime,
-                                sampleTime - previous);
+            StringAppendF(&result, "  %" PRId64 " (+%" PRId64 ")\n", sampleTime,
+                          sampleTime - previous);
         }
         previous = sampleTime;
     }
 
-    result.appendFormat("mPresentFences [%d]:\n", NUM_PRESENT_SAMPLES);
+    StringAppendF(&result, "mPresentFences [%d]:\n", NUM_PRESENT_SAMPLES);
     nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
     previous = Fence::SIGNAL_TIME_INVALID;
     for (size_t i = 0; i < NUM_PRESENT_SAMPLES; i++) {
         size_t idx = (i + mPresentSampleOffset) % NUM_PRESENT_SAMPLES;
         nsecs_t presentTime = mPresentFences[idx]->getSignalTime();
         if (presentTime == Fence::SIGNAL_TIME_PENDING) {
-            result.appendFormat("  [unsignaled fence]\n");
+            StringAppendF(&result, "  [unsignaled fence]\n");
         } else if (presentTime == Fence::SIGNAL_TIME_INVALID) {
-            result.appendFormat("  [invalid fence]\n");
+            StringAppendF(&result, "  [invalid fence]\n");
         } else if (previous == Fence::SIGNAL_TIME_PENDING ||
                    previous == Fence::SIGNAL_TIME_INVALID) {
-            result.appendFormat("  %" PRId64 "  (%.3f ms ago)\n", presentTime,
-                                (now - presentTime) / 1000000.0);
+            StringAppendF(&result, "  %" PRId64 "  (%.3f ms ago)\n", presentTime,
+                          (now - presentTime) / 1000000.0);
         } else {
-            result.appendFormat("  %" PRId64 " (+%" PRId64 " / %.3f)  (%.3f ms ago)\n", presentTime,
-                                presentTime - previous, (presentTime - previous) / (double)mPeriod,
-                                (now - presentTime) / 1000000.0);
+            StringAppendF(&result, "  %" PRId64 " (+%" PRId64 " / %.3f)  (%.3f ms ago)\n",
+                          presentTime, presentTime - previous,
+                          (presentTime - previous) / (double)mPeriod,
+                          (now - presentTime) / 1000000.0);
         }
         previous = presentTime;
     }
 
-    result.appendFormat("current monotonic time: %" PRId64 "\n", now);
+    StringAppendF(&result, "current monotonic time: %" PRId64 "\n", now);
 }
 
 // TODO(b/113612090): Figure out how much of this is still relevant.
diff --git a/services/surfaceflinger/Scheduler/DispSync.h b/services/surfaceflinger/Scheduler/DispSync.h
index 5d19093..4a90f10 100644
--- a/services/surfaceflinger/Scheduler/DispSync.h
+++ b/services/surfaceflinger/Scheduler/DispSync.h
@@ -29,7 +29,6 @@
 
 namespace android {
 
-class String8;
 class FenceTime;
 
 class DispSync {
@@ -57,7 +56,7 @@
     virtual void setIgnorePresentFences(bool ignore) = 0;
     virtual nsecs_t expectedPresentTime() = 0;
 
-    virtual void dump(String8& result) const = 0;
+    virtual void dump(std::string& result) const = 0;
 };
 
 namespace impl {
@@ -161,7 +160,7 @@
     nsecs_t expectedPresentTime();
 
     // dump appends human-readable debug info to the result string.
-    void dump(String8& result) const override;
+    void dump(std::string& result) const override;
 
 private:
     void updateModelLocked();
diff --git a/services/surfaceflinger/Scheduler/EventThread.cpp b/services/surfaceflinger/Scheduler/EventThread.cpp
index 9bee9a3..49e7ef6 100644
--- a/services/surfaceflinger/Scheduler/EventThread.cpp
+++ b/services/surfaceflinger/Scheduler/EventThread.cpp
@@ -22,18 +22,20 @@
 #include <chrono>
 #include <cstdint>
 
+#include <android-base/stringprintf.h>
+
 #include <cutils/compiler.h>
 #include <cutils/sched_policy.h>
 
 #include <gui/DisplayEventReceiver.h>
 
 #include <utils/Errors.h>
-#include <utils/String8.h>
 #include <utils/Trace.h>
 
 #include "EventThread.h"
 
 using namespace std::chrono_literals;
+using android::base::StringAppendF;
 
 // ---------------------------------------------------------------------------
 
@@ -384,18 +386,18 @@
     }
 }
 
-void EventThread::dump(String8& result) const {
+void EventThread::dump(std::string& result) const {
     std::lock_guard<std::mutex> lock(mMutex);
-    result.appendFormat("VSYNC state: %s\n", mDebugVsyncEnabled ? "enabled" : "disabled");
-    result.appendFormat("  soft-vsync: %s\n", mUseSoftwareVSync ? "enabled" : "disabled");
-    result.appendFormat("  numListeners=%zu,\n  events-delivered: %u\n",
-                        mDisplayEventConnections.size(), mVSyncEvent[0].vsync.count);
+    StringAppendF(&result, "VSYNC state: %s\n", mDebugVsyncEnabled ? "enabled" : "disabled");
+    StringAppendF(&result, "  soft-vsync: %s\n", mUseSoftwareVSync ? "enabled" : "disabled");
+    StringAppendF(&result, "  numListeners=%zu,\n  events-delivered: %u\n",
+                  mDisplayEventConnections.size(), mVSyncEvent[0].vsync.count);
     for (const wp<Connection>& weak : mDisplayEventConnections) {
         sp<Connection> connection = weak.promote();
-        result.appendFormat("    %p: count=%d\n", connection.get(),
-                            connection != nullptr ? connection->count : 0);
+        StringAppendF(&result, "    %p: count=%d\n", connection.get(),
+                      connection != nullptr ? connection->count : 0);
     }
-    result.appendFormat("  other-events-pending: %zu\n", mPendingEvents.size());
+    StringAppendF(&result, "  other-events-pending: %zu\n", mPendingEvents.size());
 }
 
 // ---------------------------------------------------------------------------
diff --git a/services/surfaceflinger/Scheduler/EventThread.h b/services/surfaceflinger/Scheduler/EventThread.h
index 5e7ed13..15b5bba 100644
--- a/services/surfaceflinger/Scheduler/EventThread.h
+++ b/services/surfaceflinger/Scheduler/EventThread.h
@@ -40,7 +40,6 @@
 
 class EventThreadTest;
 class SurfaceFlinger;
-class String8;
 
 // ---------------------------------------------------------------------------
 
@@ -76,7 +75,7 @@
     // called when receiving a hotplug event
     virtual void onHotplugReceived(DisplayType displayType, bool connected) = 0;
 
-    virtual void dump(String8& result) const = 0;
+    virtual void dump(std::string& result) const = 0;
 
     virtual void setPhaseOffset(nsecs_t phaseOffset) = 0;
 };
@@ -131,7 +130,7 @@
     // called when receiving a hotplug event
     void onHotplugReceived(DisplayType displayType, bool connected) override;
 
-    void dump(String8& result) const override;
+    void dump(std::string& result) const override;
 
     void setPhaseOffset(nsecs_t phaseOffset) override;
 
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index 4457f72..5b8cc10 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -133,7 +133,7 @@
     mConnections[handle->id]->thread->onScreenReleased();
 }
 
-void Scheduler::dump(const sp<Scheduler::ConnectionHandle>& handle, String8& result) const {
+void Scheduler::dump(const sp<Scheduler::ConnectionHandle>& handle, std::string& result) const {
     RETURN_IF_INVALID();
     mConnections.at(handle->id)->thread->dump(result);
 }
diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index 764ad00..ea90824 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -91,7 +91,7 @@
     void onScreenReleased(const sp<ConnectionHandle>& handle);
 
     // Should be called when dumpsys command is received.
-    void dump(const sp<ConnectionHandle>& handle, String8& result) const;
+    void dump(const sp<ConnectionHandle>& handle, std::string& result) const;
 
     // Offers ability to modify phase offset in the event thread.
     void setPhaseOffset(const sp<ConnectionHandle>& handle, nsecs_t phaseOffset);