Merge 61ceca6 into f486ded

Author: serbel324

ydb/core/blobstorage/dsproxy/dsproxy_get_impl.cpp

@@ -170,6 +170,7 @@ ui64 TGetImpl::GetTimeToAccelerateNs(TLogContext &logCtx, NKikimrBlobStorage::EV
         Blackboard.GetWorstPredictedDelaysNs(
                 *Info, *Blackboard.GroupQueues, queueId, nthWorst, &worstDisks);
     }
+    nthWorst = std::min(nthWorst, (ui32)worstDisks.size() - 1);
     return worstDisks[nthWorst].PredictedNs;
 }
 

ydb/core/blobstorage/dsproxy/dsproxy_strategy_base.cpp

@@ -390,6 +390,10 @@ void TStrategyBase::Prepare3dcPartPlacement(const TBlobState &state,
 
 ui32 TStrategyBase::MakeSlowSubgroupDiskMask(TBlobState &state, const TBlobStorageGroupInfo &info, TBlackboard &blackboard,
         bool isPut) {
+    if (info.GetTotalVDisksNum() == 1) {
+        // when there is only one disk, we consider it not slow
+        return 0;
+    }
     // Find the slowest disk
     switch (blackboard.AccelerationMode) {
         case TBlackboard::AccelerationModeSkipOneSlowest: {

ydb/core/blobstorage/dsproxy/dsproxy_strategy_get_m3dc_basic.h

@@ -70,32 +70,34 @@ namespace NKikimr {
             // issue request for a specific disk; returns true if the request was issued and not yet completed, otherwise
             // false
 
-            // find the slowest disk and mark it
-            switch (blackboard.AccelerationMode) {
-                case TBlackboard::AccelerationModeSkipOneSlowest: {
-                    TDiskDelayPredictions worstDisks;
-                    state.GetWorstPredictedDelaysNs(info, *blackboard.GroupQueues,
-                            HandleClassToQueueId(blackboard.GetHandleClass), 1,
-                            &worstDisks);
-
-                    // Check if the slowest disk exceptionally slow, or just not very fast
-                    i32 slowDiskSubgroupIdx = -1;
-                    if (worstDisks[1].PredictedNs > 0 && worstDisks[0].PredictedNs > worstDisks[1].PredictedNs * 2) {
-                        slowDiskSubgroupIdx = worstDisks[1].DiskIdx;
-                    }
+            if (info.GetTotalVDisksNum() > 1) {
+                // find the slowest disk and mark it
+                switch (blackboard.AccelerationMode) {
+                    case TBlackboard::AccelerationModeSkipOneSlowest: {
+                        TDiskDelayPredictions worstDisks;
+                        state.GetWorstPredictedDelaysNs(info, *blackboard.GroupQueues,
+                                HandleClassToQueueId(blackboard.GetHandleClass), 1,
+                                &worstDisks);
+
+                        // Check if the slowest disk exceptionally slow, or just not very fast
+                        i32 slowDiskSubgroupIdx = -1;
+                        if (worstDisks[1].PredictedNs > 0 && worstDisks[0].PredictedNs > worstDisks[1].PredictedNs * 2) {
+                            slowDiskSubgroupIdx = worstDisks[1].DiskIdx;
+                        }
 
-                    // Mark single slow disk
-                    for (size_t diskIdx = 0; diskIdx < state.Disks.size(); ++diskIdx) {
-                        state.Disks[diskIdx].IsSlow = false;
-                    }
-                    if (slowDiskSubgroupIdx >= 0) {
-                        state.Disks[slowDiskSubgroupIdx].IsSlow = true;
+                        // Mark single slow disk
+                        for (size_t diskIdx = 0; diskIdx < state.Disks.size(); ++diskIdx) {
+                            state.Disks[diskIdx].IsSlow = false;
+                        }
+                        if (slowDiskSubgroupIdx >= 0) {
+                            state.Disks[slowDiskSubgroupIdx].IsSlow = true;
+                        }
+                        break;
                     }
-                    break;
+                    case TBlackboard::AccelerationModeSkipMarked:
+                        // The slowest disk is already marked!
+                        break;
                 }
-                case TBlackboard::AccelerationModeSkipMarked:
-                    // The slowest disk is already marked!
-                    break;
             }
 
             // create an array defining order in which we traverse the disks

ydb/core/blobstorage/dsproxy/dsproxy_strategy_restore.h

@@ -125,16 +125,18 @@ class TRestoreStrategy : public TStrategyBase {
             return *res;
         }
 
-        // Find the slowest disk
-        TDiskDelayPredictions worstDisks;
-        state.GetWorstPredictedDelaysNs(info, *blackboard.GroupQueues,
-                HandleClassToQueueId(blackboard.PutHandleClass), 1,
-                &worstDisks);
-
-        // Check if the slowest disk exceptionally slow, or just not very fast
         TStackVec<ui32, 2> slowDiskSubgroupIdxs;
-        if (worstDisks[1].PredictedNs > 0 && worstDisks[0].PredictedNs > worstDisks[1].PredictedNs * 2) {
-            slowDiskSubgroupIdxs.push_back(worstDisks[0].DiskIdx);
+        if (info.GetTotalVDisksNum() > 1) {
+            // Find the slowest disk, if there are more than 1
+            TDiskDelayPredictions worstDisks;
+            state.GetWorstPredictedDelaysNs(info, *blackboard.GroupQueues,
+                    HandleClassToQueueId(blackboard.PutHandleClass), 1,
+                    &worstDisks);
+
+            // Check if the slowest disk exceptionally slow, or just not very fast
+            if (worstDisks[1].PredictedNs > 0 && worstDisks[0].PredictedNs > worstDisks[1].PredictedNs * 2) {
+                slowDiskSubgroupIdxs.push_back(worstDisks[0].DiskIdx);
+            }
         }
 
         bool isDone = false;