add flush pri fix and move SetSelfLowPriority into util/file_util.h

db/compaction_job.cc

@@ -59,6 +59,7 @@
 #include "util/coding.h"
 #include "util/file_reader_writer.h"
 #include "util/filename.h"
+#include "util/file_util.h"
 #include "util/log_buffer.h"
 #include "util/logging.h"
 #include "util/mutexlock.h"
@@ -76,35 +77,6 @@
 
 namespace rocksdb {
 
-namespace {
-void SetSelfThreadLowPriority() {
-#ifdef OS_LINUX
-  setpriority(
-        PRIO_PROCESS,
-        // Current thread.
-        0,
-        // Lowest priority possible.
-        19);
-#define IOPRIO_CLASS_SHIFT (13)
-#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
-    // Put schedule into IOPRIO_CLASS_IDLE class (lowest)
-    // These system calls only have an effect when used in conjunction
-    // with an I/O scheduler that supports I/O priorities. As at
-    // kernel 2.6.17 the only such scheduler is the Completely
-    // Fair Queuing (CFQ) I/O scheduler.
-    // To change scheduler:
-    //  echo cfq > /sys/block/<device_name>/queue/schedule
-    // Tunables to consider:
-    //  /sys/block/<device_name>/queue/slice_idle
-    //  /sys/block/<device_name>/queue/slice_sync
-  syscall(SYS_ioprio_set, 1,  // IOPRIO_WHO_PROCESS
-            // Current thread.
-            0,
-            IOPRIO_PRIO_VALUE(3, 0));
-#endif
-};
-}
-
 const char* GetCompactionReasonString(CompactionReason compaction_reason) {
   switch (compaction_reason) {
     case CompactionReason::kUnknown:

db/flush_job.cc

@@ -290,6 +290,7 @@ void FlushJob::Cancel() {
 }
 
 Status FlushJob::WriteLevel0Table() {
+  SetSelfThreadLowPriority();
   AutoThreadOperationStageUpdater stage_updater(
       ThreadStatus::STAGE_FLUSH_WRITE_L0);
   db_mutex_->AssertHeld();

util/file_util.cc

@@ -8,6 +8,11 @@
 #include <string>
 #include <algorithm>
 
+#include <unistd.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+
 #include "rocksdb/env.h"
 #include "util/sst_file_manager_impl.h"
 #include "util/file_reader_writer.h"
@@ -111,4 +116,31 @@ Status DeleteDBFile(const ImmutableDBOptions* db_options,
 #endif
 }
 
+void SetSelfThreadLowPriority() {
+#ifdef OS_LINUX
+  setpriority(
+        PRIO_PROCESS,
+        // Current thread.
+        0,
+        // Lowest priority possible.
+        19);
+#define IOPRIO_CLASS_SHIFT (13)
+#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
+    // Put schedule into IOPRIO_CLASS_IDLE class (lowest)
+    // These system calls only have an effect when used in conjunction
+    // with an I/O scheduler that supports I/O priorities. As at
+    // kernel 2.6.17 the only such scheduler is the Completely
+    // Fair Queuing (CFQ) I/O scheduler.
+    // To change scheduler:
+    //  echo cfq > /sys/block/<device_name>/queue/schedule
+    // Tunables to consider:
+    //  /sys/block/<device_name>/queue/slice_idle
+    //  /sys/block/<device_name>/queue/slice_sync
+  syscall(SYS_ioprio_set, 1,  // IOPRIO_WHO_PROCESS
+            // Current thread.
+            0,
+            IOPRIO_PRIO_VALUE(3, 0));
+#endif
+}
+
 }  // namespace rocksdb

util/file_util.h

@@ -30,4 +30,6 @@ extern Status DeleteDBFile(const ImmutableDBOptions* db_options,
                             const std::string& path_to_sync,
                             const bool force_bg);
 
+extern void SetSelfThreadLowPriority();
+
 }  // namespace rocksdb