--- vdr-1.3.36.org/config.c	2005-09-09 17:08:59.000000000 +0200
+++ vdr-1.3.36/config.c	2005-11-21 22:17:55.000000000 +0100
@@ -453,6 +453,7 @@ bool cSetup::Parse(const char *Name, con
   else if (!strcasecmp(Name, "UseSmallFont"))        UseSmallFont       = atoi(Value);
   else if (!strcasecmp(Name, "MaxVideoFileSize"))    MaxVideoFileSize   = atoi(Value);
   else if (!strcasecmp(Name, "SplitEditedFiles"))    SplitEditedFiles   = atoi(Value);
+  else if (!strcasecmp(Name, "WriteStrategy"))       WriteStrategy      = atoi(Value);
   else if (!strcasecmp(Name, "MinEventTimeout"))     MinEventTimeout    = atoi(Value);
   else if (!strcasecmp(Name, "MinUserInactivity"))   MinUserInactivity  = atoi(Value);
   else if (!strcasecmp(Name, "MultiSpeedMode"))      MultiSpeedMode     = atoi(Value);
@@ -518,6 +519,7 @@ bool cSetup::Save(void)
   Store("UseSmallFont",       UseSmallFont);
   Store("MaxVideoFileSize",   MaxVideoFileSize);
   Store("SplitEditedFiles",   SplitEditedFiles);
+  Store("WriteStrategy",      WriteStrategy);
   Store("MinEventTimeout",    MinEventTimeout);
   Store("MinUserInactivity",  MinUserInactivity);
   Store("MultiSpeedMode",     MultiSpeedMode);
--- vdr-1.3.36.org/config.h	2005-11-04 16:55:05.000000000 +0100
+++ vdr-1.3.36/config.h	2005-11-21 21:57:52.000000000 +0100
@@ -249,6 +249,7 @@ public:
   int UseSmallFont;
   int MaxVideoFileSize;
   int SplitEditedFiles;
+  int WriteStrategy;
   int MinEventTimeout, MinUserInactivity;
   int MultiSpeedMode;
   int ShowReplayMode;
--- vdr-1.3.36.org/cutter.c	2005-10-31 13:26:44.000000000 +0100
+++ vdr-1.3.36/cutter.c	2005-11-22 19:29:03.000000000 +0100
@@ -66,6 +66,7 @@ void cCuttingThread::Action(void)
      toFile = toFileName->Open();
      if (!fromFile || !toFile)
         return;
+     fromFile->setreadahead(MEGABYTE(5));
      int Index = Mark->position;
      Mark = fromMarks.Next(Mark);
      int FileSize = 0;
@@ -90,6 +91,7 @@ void cCuttingThread::Action(void)
            if (fromIndex->Get(Index++, &FileNumber, &FileOffset, &PictureType, &Length)) {
               if (FileNumber != CurrentFileNumber) {
                  fromFile = fromFileName->SetOffset(FileNumber, FileOffset);
+                 fromFile->setreadahead(MEGABYTE(5));
                  CurrentFileNumber = FileNumber;
                  }
               if (fromFile) {
--- vdr-1.3.36.org/menu.c	2005-11-05 18:29:22.000000000 +0100
+++ vdr-1.3.36/menu.c	2005-11-21 22:14:38.000000000 +0100
@@ -2270,6 +2270,7 @@ cMenuSetupRecord::cMenuSetupRecord(void)
   Add(new cMenuEditIntItem( tr("Setup.Recording$Instant rec. time (min)"),   &data.InstantRecordTime, 1, MAXINSTANTRECTIME));
   Add(new cMenuEditIntItem( tr("Setup.Recording$Max. video file size (MB)"), &data.MaxVideoFileSize, MINVIDEOFILESIZE, MAXVIDEOFILESIZE));
   Add(new cMenuEditBoolItem(tr("Setup.Recording$Split edited files"),        &data.SplitEditedFiles));
+  Add(new cMenuEditIntItem( tr("Setup.Recording$Write strategy"),            &data.WriteStrategy, 0, 2));
 }
 
 // --- cMenuSetupReplay ------------------------------------------------------
--- vdr-1.3.36.org/tools.c	2005-11-04 17:33:18.000000000 +0100
+++ vdr-1.3.36/tools.c	2005-11-22 19:30:25.000000000 +0100
@@ -7,6 +7,7 @@
  * $Id: tools.c 1.103 2005/11/04 16:33:18 kls Exp $
  */
 
+#include "config.h"
 #include "tools.h"
 #include <ctype.h>
 #include <dirent.h>
@@ -851,8 +852,7 @@ bool cSafeFile::Close(void)
 
 // --- cUnbufferedFile -------------------------------------------------------
 
-#define READ_AHEAD MEGABYTE(2)
-#define WRITE_BUFFER MEGABYTE(10)
+#define WRITE_BUFFER KILOBYTE(800)
 
 cUnbufferedFile::cUnbufferedFile(void)
 {
@@ -868,23 +868,28 @@ int cUnbufferedFile::Open(const char *Fi
 {
   Close();
   fd = open(FileName, Flags, Mode);
-  begin = end = ahead = -1;
+  curpos = 0;
+  begin = lastpos = ahead = 0;
+  readahead = 128*1024;
+  pendingreadahead = 0;
   written = 0;
+  totwritten = 0;
+  if (fd >= 0) {
+     // we really mean POSIX_FADV_SEQUENTIAL, but we do our own readahead
+     // so turn off the kernel one.
+     if (Setup.WriteStrategy!=1)
+        posix_fadvise(fd, 0, 0, POSIX_FADV_RANDOM);
+     }
   return fd;
 }
 
 int cUnbufferedFile::Close(void)
 {
   if (fd >= 0) {
-     if (ahead > end)
-        end = ahead;
-     if (begin >= 0 && end > begin) {
-        //dsyslog("close buffer: %d (flush: %d bytes, %ld-%ld)", fd, written, begin, end);
-        if (written)
-           fdatasync(fd);
-        posix_fadvise(fd, begin, end - begin, POSIX_FADV_DONTNEED);
-        }
-     begin = end = ahead = -1;
+     if (totwritten)
+        fdatasync(fd);
+     posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+     begin = lastpos = ahead = 0;
      written = 0;
      }
   int OldFd = fd;
@@ -894,40 +899,105 @@ int cUnbufferedFile::Close(void)
 
 off_t cUnbufferedFile::Seek(off_t Offset, int Whence)
 {
-  if (fd >= 0)
-     return lseek(fd, Offset, Whence);
-  return -1;
+  //dsyslog("Seek: fd: %d offs: %ld whence: %d diff: %ld", fd, (long)Offset, Whence, Offset-curpos);
+  if (Whence == SEEK_SET && Offset == curpos)
+     return curpos;
+  
+  curpos = lseek(fd, Offset, Whence);
+  return curpos;
 }
 
+// when replaying and going eg FF->PLAY the position jumps back 2..8M
+// hence we might not want to drop that data at once. 
+// Ignoring for now to avoid making this even more complex, but we could
+// at least try to handle the common cases
+// (PLAY->FF->PLAY, small jumps, moving editing marks etc)
+
 ssize_t cUnbufferedFile::Read(void *Data, size_t Size)
 {
   if (fd >= 0) {
-     off_t pos = lseek(fd, 0, SEEK_CUR);
-     // jump forward - adjust end position
-     if (pos > end)
-        end = pos;
-     // after adjusting end - don't clear more than previously requested
-     if (end > ahead)
-        end = ahead;
-     // jump backward - drop read ahead of previous run
-     if (pos < begin)
-        end = ahead;
-     if (begin >= 0 && end > begin)
-        posix_fadvise(fd, begin - KILOBYTE(200), end - begin + KILOBYTE(200), POSIX_FADV_DONTNEED);//XXX macros/parameters???
-     begin = pos;
+     off_t jumped = curpos-lastpos; // nonzero means we're not at the last offset - some kind of jump happened.
+     if (jumped) {
+        pendingreadahead += ahead-lastpos+MEGABYTE(4);
+        // jumped forward? - treat as if we did read all the way to current pos.
+        if (jumped >= 0) {
+           lastpos = curpos;
+           // but clamp at ahead so we don't clear more than previously requested.
+           // (would be mostly harmless anyway, unless we got more than one reader of this file)
+           // add a little extra readahead, JIC the kernel prefethed more than we requested.
+           if (lastpos > (ahead+MEGABYTE(4)))
+              lastpos = ahead+MEGABYTE(4);
+        }
+        // jumped backward? - drop both last read _and_ read-ahead
+        else
+	   if (curpos < begin)
+              lastpos = ahead+MEGABYTE(4);
+           // jumped backward, but still inside prev read window? - pretend we read less.
+           else /* if (curpos >= begin) */
+              lastpos = curpos;
+        }
+        
      ssize_t bytesRead = safe_read(fd, Data, Size);
+     
+     // now drop all data accesed during _previous_ Read().
+     // but try to merge the fadvise calls a bit in order to reduce overhead.
+     if (Setup.WriteStrategy!=1 && begin >= 0 && lastpos > begin)
+        if (jumped || (size_t)(lastpos-begin) > readahead) {
+           //dsyslog("taildrop:    %ld..%ld size %ld", begin, lastpos, lastpos-begin);
+           posix_fadvise(fd, begin-4095, lastpos-begin+4095*2, POSIX_FADV_DONTNEED);
+           begin = curpos;
+           }
+        
      if (bytesRead > 0) {
-        pos += bytesRead;
-        end = pos;
+        curpos += bytesRead;
         // this seems to trigger a non blocking read - this
         // may or may not have been finished when we will be called next time.
         // If it is not finished we can't release the not yet filled buffers.
         // So this is commented out till we find a better solution.
-        //posix_fadvise(fd, pos, READ_AHEAD, POSIX_FADV_WILLNEED);
-        ahead = pos + READ_AHEAD;
+        
+        // Hmm, it's obviously harmless if we're actually going to read the data
+        // -- the whole point of read-ahead is to start the IO early...
+        // The comment above applies only when we jump somewhere else _before_ the
+        // IO started here finishes. How common would that be? Could be handled eg
+        // by posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED) called some time after
+        // we detect a jump. Ignoring this for now. /AS
+
+        // Ugh, it seems to cause some "leaks" at every jump... Either the
+        // brute force approach mentioned above should work (it's not like this is
+        // much different than O_DIRECT) or keeping notes about the ahead reads and
+        // flushing them after some time. the latter seems overkill though, trying
+        // the former...
+
+        //dsyslog("jump: %06ld ra: %06ld size: %ld", jumped, (long)readahead, (long)Size);
+
+        // no jump? also permit small jump still inside readahead window (FF).
+        if (Setup.WriteStrategy!=1 && jumped>=0 && jumped<=(off_t)readahead) {
+           if ( readahead < Size*32 ) { // automagically tune readahead size.
+              readahead = Size*32;
+              //dsyslog("Readahead for fd: %d increased to %ld", fd, (long)readahead);
+              }
+           if (ahead<(off_t)(curpos+readahead/2)) {
+              posix_fadvise(fd, curpos, readahead, POSIX_FADV_WILLNEED);
+              ahead = curpos + readahead;
+              }
+           }
+        else {
+           // jumped - we really don't want any readahead now. otherwise
+           // eg fast-rewind gets in trouble.
+           ahead = curpos;
+
+           // flush it all; mostly to get rid of nonflushed readahead coming
+           // from _previous_ jumps. ratelimited.
+           // the accounting is _very_ unaccurate, i've seen ~50M get flushed
+           // when the limit was set to 4M. As long as this triggers after
+           // _some_ jumps we should be ok though.
+           if (Setup.WriteStrategy!=1 && pendingreadahead>MEGABYTE(20)) {
+              pendingreadahead = 0;
+              posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+              }
+           }
         }
-     else
-        end = pos;
+     lastpos = curpos;
      return bytesRead;
      }
   return -1;
@@ -936,25 +1006,35 @@ ssize_t cUnbufferedFile::Read(void *Data
 ssize_t cUnbufferedFile::Write(const void *Data, size_t Size)
 {
   if (fd >=0) {
-     off_t pos = lseek(fd, 0, SEEK_CUR);
      ssize_t bytesWritten = safe_write(fd, Data, Size);
      if (bytesWritten >= 0) {
+        curpos += bytesWritten;
         written += bytesWritten;
         if (begin >= 0) {
-           if (pos < begin)
-              begin = pos;
+           if (curpos < begin)
+              begin = curpos;
            }
         else
-           begin = pos;
-        if (pos + bytesWritten > end)
-           end = pos + bytesWritten;
+           begin = curpos;
+        if (curpos + bytesWritten > lastpos)
+           lastpos = curpos + bytesWritten;
         if (written > WRITE_BUFFER) {
-           //dsyslog("flush buffer: %d (%d bytes, %ld-%ld)", fd, written, begin, end);
-           fdatasync(fd);
-           if (begin >= 0 && end > begin)
-              posix_fadvise(fd, begin, end - begin, POSIX_FADV_DONTNEED);
-           begin = end = -1;
+           //dsyslog("flush buffer: %d (%d bytes, %ld-%ld)", fd, written, begin, lastpos);
+           totwritten += written;
+           if (Setup.WriteStrategy!=1 && begin >= 0 && lastpos > begin) {
+              off_t headdrop = max(begin,WRITE_BUFFER*2L);
+              posix_fadvise(fd, begin-headdrop, lastpos - begin + headdrop, POSIX_FADV_DONTNEED);
+              }
+           begin = lastpos = 0;
            written = 0;
+           // the above fadvise() works when recording, but seems to leave cached
+           // data around when writing at a high rate (eg cutting). Hence...
+           if (Setup.WriteStrategy!=1 && totwritten>MEGABYTE(20)) {
+              //if (Setup.WriteStrategy==2)
+              fdatasync(fd);
+              posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+              totwritten = 0;
+              }
            }
         }
      return bytesWritten;
--- vdr-1.3.36.org/tools.h	2005-11-05 11:54:39.000000000 +0100
+++ vdr-1.3.36/tools.h	2005-11-22 16:16:16.000000000 +0100
@@ -205,10 +205,14 @@ public:
 class cUnbufferedFile {
 private:
   int fd;
+  off_t curpos;
   off_t begin;
-  off_t end;
+  off_t lastpos;
   off_t ahead;
+  size_t pendingreadahead;
+  size_t readahead;
   ssize_t written;
+  ssize_t totwritten;
 public:
   cUnbufferedFile(void);
   ~cUnbufferedFile();
@@ -218,6 +222,7 @@ public:
   ssize_t Read(void *Data, size_t Size);
   ssize_t Write(const void *Data, size_t Size);
   static cUnbufferedFile *Create(const char *FileName, int Flags, mode_t Mode = DEFFILEMODE);
+  void setreadahead(size_t ra) { readahead = ra; };
   };
 
 class cLockFile {
