Changeset 9514

Timestamp:

Nov 10, 2009, 5:26:04 PM (13 years ago)

Author:

charles

Message:

(trunk libT) #2551: when uploading to peers, prefetch local data from disk

File:

• trunk/libtransmission/peer-msgs.c (modified) (8 diffs)

trunk/libtransmission/peer-msgs.c

@@ -173 +173 @@
     int             desiredRequestCount;
 
+    int             prefetchCount;
+
     /* how long the outMessages batch should be allowed to grow before
      * it's flushed -- some messages (like requests >:) should be sent
@@ -198 +200 @@
     struct peer_request    peerAskedFor[REQQ];
     int                    peerAskedForCount;
-    
+ 
     tr_pex               * pex;
     tr_pex               * pex6;
@@ -837 +839 @@
         tr_bencDictAddRaw( &val, "ipv6", ipv6, 16 );
     tr_bencDictAddInt( &val, "p", tr_sessionGetPeerPort( getSession(msgs) ) );
-    tr_bencDictAddInt( &val, "reqq", REQQ ); 
+    tr_bencDictAddInt( &val, "reqq", REQQ );
     tr_bencDictAddInt( &val, "upload_only", tr_torrentIsSeed( msgs->torrent ) );
     tr_bencDictAddStr( &val, "v", TR_NAME " " USERAGENT_PREFIX );
@@ -1557 +1559 @@
         double rate;
         const int floor = 16;
-        const int seconds = REQUEST_BUF_SECS; 
+        const int seconds = REQUEST_BUF_SECS;
 
         /* Get the rate limit we should use.
@@ -1595 +1597 @@
         tr_block_index_t * blocks = tr_new( tr_block_index_t, numwant );
 
-        tr_peerMgrGetNextRequests( msgs->torrent, msgs->peer, numwant, blocks, &n ); 
+        tr_peerMgrGetNextRequests( msgs->torrent, msgs->peer, numwant, blocks, &n );
 
         for( i=0; i<n; ++i )
@@ -1607 +1609 @@
 
         tr_free( blocks );
+    }
+}
+
+static void
+prefetchPieces( tr_peermsgs *msgs )
+{
+    int i;
+    uint64_t next = 0;
+
+    /* Maintain at least 8 prefetched blocks per unchoked peer, but allow
+       up to 4 extra blocks if that would cause sequential writes. */
+    for( i=msgs->prefetchCount; i<msgs->peerAskedForCount; ++i )
+    {
+        const struct peer_request * req = msgs->peerAskedFor + i;
+        const uint64_t begin = tr_pieceOffset( msgs->torrent, req->index, req->offset, 0 );
+        const uint64_t end = begin + req->length;
+        const tr_bool isSequential = next == begin;
+
+        if( ( i >= 12 ) || ( !isSequential && ( i >= 8 ) ) )
+            break;
+
+        tr_ioPrefetch( msgs->torrent, req->index, req->offset, req->length );
+        ++msgs->prefetchCount;
+
+        next = end;
     }
 }
@@ -1646 +1673 @@
         && popNextRequest( msgs, &req ) )
     {
+        --msgs->prefetchCount;
+
         if( requestIsValid( msgs, &req )
             && tr_cpPieceIsComplete( &msgs->torrent->completion, req.index ) )
@@ -1691 +1720 @@
             protocolSendReject( msgs, &req );
         }
+
+        prefetchPieces( msgs );
     }