Optimize detection of file available for prefetching.

xrootd · Mar 9, 2016 · 4af1628 · 4af1628
1 parent 13c6e23
commit 4af1628
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Showing 3 changed files with 45 additions and 49 deletions.
diff --git a/src/XrdFileCache/XrdFileCache.cc b/src/XrdFileCache/XrdFileCache.cc
@@ -258,9 +258,6 @@ Cache::GetNextFileToPrefetch()
    size_t l = m_files.size();
    int idx = rand() % l;
    File* f = m_files[idx];
-
-   std::random_shuffle(m_files.begin(), m_files.end());
-   File* f = m_files.back();
    f->MarkPrefetch();
    m_prefetch_condVar.UnLock();
    return f;

diff --git a/src/XrdFileCache/XrdFileCacheFile.cc b/src/XrdFileCache/XrdFileCacheFile.cc
@@ -49,6 +49,8 @@ namespace XrdPosixGlobals
 namespace
 {
 const int PREFETCH_MAX_ATTEMPTS = 10;
+const size_t PREFETCH_MAX_BLOCKS=5;
+
 class DiskSyncer : public XrdJob
 {
 private:
@@ -85,6 +87,7 @@ m_syncer(new DiskSyncer(this, "XrdFileCache::DiskSyncer")),
 m_non_flushed_cnt(0),
 m_in_sync(false),
 m_downloadCond(0),
+m_prefetchState(kOn),
 m_prefetchReadCnt(0),
 m_prefetchHitCnt(0),
 m_prefetchScore(1),
@@ -213,7 +216,8 @@ bool File::InitiateClose()
 
    m_stateCond.Lock();
    m_stopping = true;
-   m_stateCond.UnLock(); 
+   m_stateCond.UnLock();
+   m_prefetchState = kCanceled; 
    if (m_cfi.IsComplete()) return false; // AMT maybe map size is here more meaningfull, but might hold block state lock
    return true;
 }
@@ -354,6 +358,10 @@ Block* File::RequestBlock(int i, bool prefetch)
    if (status.IsOK()) {
       clLog()->Dump(XrdCl::AppMsg, "File::RequestBlock() this = %p, b=%p, this idx=%d  pOn=(%d) %s", (void*)this, (void*)b, i, prefetch, lPath());
       m_block_map[i] = b;
+
+      if (m_prefetchState == kOn && m_block_map.size() > PREFETCH_MAX_BLOCKS) {
+         m_prefetchState = kHold;
+      }
       return b;
    }
    else {
@@ -807,7 +815,6 @@ void File::inc_ref_count(Block* b)
 
 //______________________________________________________________________________
 
-
 void File::dec_ref_count(Block* b)
 {
    // Method always called under lock
@@ -832,6 +839,9 @@ void File::free_block(Block* b)
    else {
       cache()->RAMBlockReleased();
    }
+
+   if (m_prefetchState == kHold && m_block_map.size() < PREFETCH_MAX_BLOCKS)
+      m_prefetchState = kOn;
 }
 
 //------------------------------------------------------------------------------
@@ -919,57 +929,42 @@ void File::AppendIOStatToFileInfo()
 //______________________________________________________________________________
 void File::Prefetch()
 {
-   bool stopping = false;
-   m_stateCond.Lock();
-   stopping = m_stopping;
-   m_stateCond.UnLock();
-
 
-   if (!stopping) {
+   if (m_prefetchState == kOn) {
 
-       //  clLog()->Dump(XrdCl::AppMsg, "File::Prefetch enter to check download status \n");
+      //  clLog()->Dump(XrdCl::AppMsg, "File::Prefetch enter to check download status \n");
       XrdSysCondVarHelper _lck(m_downloadCond);
       //      clLog()->Dump(XrdCl::AppMsg, "File::Prefetch enter to check download status BEGIN %s \n", lPath());
-      if (m_cfi.IsComplete() == false && m_block_map.size() < 3)
-      {
 
-         // check index not on disk and not in RAM
-         bool found = false;
-         for (int f=0; f < m_cfi.GetSizeInBits(); ++f)
-         {
-             // clLog()->Dump(XrdCl::AppMsg, "File::Prefetch test bit %d", f);
-            if (!m_cfi.TestBit(f))
-            {    
-               BlockMap_i bi = m_block_map.find(f);
-               if (bi == m_block_map.end()) {
-                  clLog()->Dump(XrdCl::AppMsg, "File::Prefetch take block %d %s", f, lPath());
-                  cache()->RequestRAMBlock();
-                  RequestBlock(f, true);
-                  m_prefetchReadCnt++;
-                  m_prefetchScore = float(m_prefetchHitCnt)/m_prefetchReadCnt;
-                  found = true;
-                  break;
-               }
+      // check index not on disk and not in RAM
+      bool found = false;
+      for (int f=0; f < m_cfi.GetSizeInBits(); ++f)
+      {
+         // clLog()->Dump(XrdCl::AppMsg, "File::Prefetch test bit %d", f);
+         if (!m_cfi.TestBit(f))
+         {    
+            BlockMap_i bi = m_block_map.find(f);
+            if (bi == m_block_map.end()) {
+               clLog()->Dump(XrdCl::AppMsg, "File::Prefetch take block %d %s", f, lPath());
+               cache()->RequestRAMBlock();
+               RequestBlock(f, true);
+               m_prefetchReadCnt++;
+               m_prefetchScore = float(m_prefetchHitCnt)/m_prefetchReadCnt;
+               found = true;
+               break;
             }
          }
-         if (!found)  { 
-            clLog()->Dump(XrdCl::AppMsg, "File::Prefetch no free blcok found ");
-            m_cfi.CheckComplete();
-            //  assert (m_cfi.IsComplete());
-            // it is possible all missing blocks are in map but downlaoded status is still not complete
-            clLog()->Dump(XrdCl::AppMsg, "File::Prefetch -- unlikely to happen ... file seem to be complete %s", lPath());
-            // remove block from map
-            cache()->DeRegisterPrefetchFile(this); 
-         }
-         clLog()->Dump(XrdCl::AppMsg, "File::Prefetch end");
-      } /*
-      else if (m_block_map.size() >= 3) {
-         clLog()->Dump(XrdCl::AppMsg,"skip prefetch %s ", lPath());
-         for (BlockMap_i it = m_block_map.begin(); it != m_block_map.end(); ++it )
-         {
-            clLog()->Dump(XrdCl::AppMsg, "block  idx = %d, ref_count = %d, prefetch=%d  [%s]", it->first, it->second->m_refcnt, it->second->m_prefetch, lPath());
-         }
-         }*/
+      }
+      if (!found)  { 
+         clLog()->Dump(XrdCl::AppMsg, "File::Prefetch no free blcok found ");
+         m_cfi.CheckComplete();
+         //  assert (m_cfi.IsComplete());
+         // it is possible all missing blocks are in map but downlaoded status is still not complete
+         clLog()->Dump(XrdCl::AppMsg, "File::Prefetch -- unlikely to happen ... file seem to be complete %s", lPath());
+         // remove block from map
+         cache()->DeRegisterPrefetchFile(this); 
+      }
+      clLog()->Dump(XrdCl::AppMsg, "File::Prefetch end");
    }
 
    UnMarkPrefetch();

diff --git a/src/XrdFileCache/XrdFileCacheFile.hh b/src/XrdFileCache/XrdFileCacheFile.hh
@@ -87,6 +87,8 @@ namespace XrdFileCache
    class File
    {
    private:
+      enum PrefetchState_e { kOn, kHold, kCanceled };
+
       XrdOucCacheIO  &m_input;          //!< original data source
       XrdOssDF       *m_output;         //!< file handle for data file on disk
       XrdOssDF       *m_infoFile;       //!< file handle for data-info file on disk
@@ -123,6 +125,8 @@ namespace XrdFileCache
 
       Stats           m_stats;      //!< cache statistics, used in IO detach
 
+      PrefetchState_e m_prefetchState;
+
       int             m_prefetchReadCnt;
       int             m_prefetchHitCnt;
       float           m_prefetchScore; //cached