From 116abbe05e491b61c6cd3541e5c8db1e72122ab6 Mon Sep 17 00:00:00 2001
From: Klaus Schmidinger <vdr@tvdr.de>
Date: Sat, 4 Feb 2006 14:12:17 +0100
Subject: Improved cUnbufferedFile
---
CONTRIBUTORS | 1 +
HISTORY | 3 ++
cutter.c | 7 ++-
tools.c | 159 +++++++++++++++++++++++++++++++++++++----------------------
tools.h | 13 +++--
5 files changed, 121 insertions(+), 62 deletions(-)
diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 42c8a892..fd9e2c12 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -271,6 +271,7 @@ Artur Skawina <skawina@geocities.com>
for improving the font file generation in the Makefile
for pointing out a problem with the ERR macro defined by ncurses.h
for a patch that contained a fix for checking toFile in cCuttingThread::Action()
+ for improving cUnbufferedFile
Werner Fink <werner@suse.de>
for making I/O more robust by handling EINTR
diff --git a/HISTORY b/HISTORY
index efd64f9e..514b9df4 100644
--- a/HISTORY
+++ b/HISTORY
@@ -4293,3 +4293,6 @@ Video Disk Recorder Revision History
(reported by Udo Richter).
- Fixed handling the "Setup/OSD/Menu button closes" option when set to 'yes' in
case a replay is active (thanks to Udo Richter).
+- Improved cUnbufferedFile; USE_FADVISE is now defined in tools.c by default, so
+ if you don't want to use "fadvise" you need to comment out that line (thanks to
+ Artur Skawina).
diff --git a/cutter.c b/cutter.c
index 6d3a152d..ee4b1a5f 100644
--- a/cutter.c
+++ b/cutter.c
@@ -4,7 +4,7 @@
* See the main source file 'vdr.c' for copyright information and
* how to reach the author.
*
- * $Id: cutter.c 1.12 2006/01/27 13:45:00 kls Exp $
+ * $Id: cutter.c 1.13 2006/02/04 13:40:20 kls Exp $
*/
#include "cutter.h"
@@ -66,6 +66,8 @@ void cCuttingThread::Action(void)
toFile = toFileName->Open();
if (!fromFile || !toFile)
return;
+ fromFile->SetReadAhead(MEGABYTE(20));
+ toFile->SetReadAhead(MEGABYTE(20));
int Index = Mark->position;
Mark = fromMarks.Next(Mark);
int FileSize = 0;
@@ -90,6 +92,7 @@ void cCuttingThread::Action(void)
if (fromIndex->Get(Index++, &FileNumber, &FileOffset, &PictureType, &Length)) {
if (FileNumber != CurrentFileNumber) {
fromFile = fromFileName->SetOffset(FileNumber, FileOffset);
+ fromFile->SetReadAhead(MEGABYTE(20));
CurrentFileNumber = FileNumber;
}
if (fromFile) {
@@ -122,6 +125,7 @@ void cCuttingThread::Action(void)
error = "toFile 1";
break;
}
+ toFile->SetReadAhead(MEGABYTE(20));
FileSize = 0;
}
LastIFrame = 0;
@@ -162,6 +166,7 @@ void cCuttingThread::Action(void)
error = "toFile 2";
break;
}
+ toFile->SetReadAhead(MEGABYTE(20));
FileSize = 0;
}
}
diff --git a/tools.c b/tools.c
index 031c120a..e9b2cb17 100644
--- a/tools.c
+++ b/tools.c
@@ -4,7 +4,7 @@
* See the main source file 'vdr.c' for copyright information and
* how to reach the author.
*
- * $Id: tools.c 1.112 2006/01/20 14:01:28 kls Exp $
+ * $Id: tools.c 1.113 2006/02/04 14:07:30 kls Exp $
*/
#include "tools.h"
@@ -1054,10 +1054,9 @@ bool cSafeFile::Close(void)
// --- cUnbufferedFile -------------------------------------------------------
-//#define USE_FADVISE
+#define USE_FADVISE
-#define READ_AHEAD MEGABYTE(2)
-#define WRITE_BUFFER MEGABYTE(10)
+#define WRITE_BUFFER KILOBYTE(800)
cUnbufferedFile::cUnbufferedFile(void)
{
@@ -1073,8 +1072,17 @@ int cUnbufferedFile::Open(const char *FileName, int Flags, mode_t Mode)
{
Close();
fd = open(FileName, Flags, Mode);
- begin = end = ahead = -1;
+ curpos = 0;
+#ifdef USE_FADVISE
+ begin = lastpos = ahead = 0;
+ cachedstart = 0;
+ cachedend = 0;
+ readahead = KILOBYTE(128);
written = 0;
+ totwritten = 0;
+ if (fd >= 0)
+ posix_fadvise(fd, 0, 0, POSIX_FADV_RANDOM); // we could use POSIX_FADV_SEQUENTIAL, but we do our own readahead, disabling the kernel one.
+#endif
return fd;
}
@@ -1082,16 +1090,9 @@ int cUnbufferedFile::Close(void)
{
#ifdef USE_FADVISE
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;
- written = 0;
+ if (totwritten) // if we wrote anything make sure the data has hit the disk before
+ fdatasync(fd); // calling fadvise, as this is our last chance to un-cache it.
+ posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
}
#endif
int OldFd = fd;
@@ -1099,45 +1100,81 @@ int cUnbufferedFile::Close(void)
return close(OldFd);
}
+// When replaying and going e.g. FF->PLAY the position jumps back 2..8M
+// hence we do not want to drop recently accessed data at once.
+// We try to handle the common cases such as PLAY->FF->PLAY, small
+// jumps, moving editing marks etc.
+
+#define FADVGRAN KILOBYTE(4) // AKA fadvise-chunk-size; PAGE_SIZE or getpagesize(2) would also work.
+#define READCHUNK MEGABYTE(8)
+
+void cUnbufferedFile::SetReadAhead(size_t ra)
+{
+ readahead = ra;
+}
+
+int cUnbufferedFile::FadviseDrop(off_t Offset, off_t Len)
+{
+ // rounding up the window to make sure that not PAGE_SIZE-aligned data gets freed.
+ return posix_fadvise(fd, Offset - (FADVGRAN - 1), Len + (FADVGRAN - 1) * 2, POSIX_FADV_DONTNEED);
+}
+
off_t cUnbufferedFile::Seek(off_t Offset, int Whence)
{
- if (fd >= 0)
- return lseek(fd, Offset, Whence);
- return -1;
+ if (Whence == SEEK_SET && Offset == curpos)
+ return curpos;
+ curpos = lseek(fd, Offset, Whence);
+ return curpos;
}
ssize_t cUnbufferedFile::Read(void *Data, size_t Size)
{
if (fd >= 0) {
#ifdef USE_FADVISE
- 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
+ if ((cachedstart < cachedend) && (curpos < cachedstart || curpos > cachedend)) {
+ FadviseDrop(cachedstart, cachedend-cachedstart);
+ cachedstart = curpos;
+ cachedend = curpos;
+ }
+ cachedstart = min(cachedstart, curpos);
#endif
ssize_t bytesRead = safe_read(fd, Data, Size);
#ifdef USE_FADVISE
if (bytesRead > 0) {
- pos += bytesRead;
- end = pos;
- // 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;
+ curpos += bytesRead;
+ cachedend = max(cachedend, curpos);
+
+ // Read ahead:
+ // no jump? (allow small forward jump still inside readahead window).
+ if (jumped >= 0 && jumped <= (off_t)readahead) {
+ // Trigger the readahead IO, but only if we've used at least
+ // 1/2 of the previously requested area. This avoids calling
+ // fadvise() after every read() call.
+ if (ahead - curpos < (off_t)(readahead - readahead / 2)) {
+ posix_fadvise(fd, curpos, readahead, POSIX_FADV_WILLNEED);
+ ahead = curpos + readahead;
+ cachedend = max(cachedend, ahead);
+ }
+ if (readahead < Size * 32) { // automagically tune readahead size.
+ readahead = Size * 32;
+ }
+ }
+ else
+ ahead = curpos; // jumped -> we really don't want any readahead. otherwise eg fast-rewind gets in trouble.
}
- else
- end = pos;
+
+ if (cachedstart < cachedend) {
+ if (curpos - cachedstart > READCHUNK * 2) {
+ FadviseDrop(cachedstart, curpos - READCHUNK - cachedstart);
+ cachedstart = curpos - READCHUNK;
+ }
+ else if (cachedend > ahead && cachedend - curpos > READCHUNK * 2) {
+ FadviseDrop(curpos + READCHUNK, cachedend - curpos + READCHUNK);
+ cachedend = curpos + READCHUNK;
+ }
+ }
+ lastpos = curpos;
#endif
return bytesRead;
}
@@ -1147,28 +1184,34 @@ ssize_t cUnbufferedFile::Read(void *Data, size_t Size)
ssize_t cUnbufferedFile::Write(const void *Data, size_t Size)
{
if (fd >=0) {
-#ifdef USE_FADVISE
- off_t pos = lseek(fd, 0, SEEK_CUR);
-#endif
ssize_t bytesWritten = safe_write(fd, Data, Size);
#ifdef USE_FADVISE
- if (bytesWritten >= 0) {
+ if (bytesWritten > 0) {
+ begin = min(begin, curpos);
+ curpos += bytesWritten;
written += bytesWritten;
- if (begin >= 0) {
- if (pos < begin)
- begin = pos;
- }
- else
- begin = pos;
- if (pos + bytesWritten > end)
- end = pos + bytesWritten;
+ lastpos = max(lastpos, curpos);
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;
+ if (lastpos > begin) {
+ off_t headdrop = min(begin, WRITE_BUFFER * 2L);
+ posix_fadvise(fd, begin - headdrop, lastpos - begin + headdrop, POSIX_FADV_DONTNEED);
+ }
+ begin = lastpos = max(0L, curpos - (KILOBYTE(4) - 1));
+ totwritten += written;
written = 0;
+ // The above fadvise() works when writing slowly (recording), but could
+ // leave cached data around when writing at a high rate (cutting).
+ // Also, it seems in some setups, the above does not trigger any I/O and
+ // the fdatasync() call below has to do all the work (reiserfs with some
+ // kind of write gathering enabled).
+ // We add 'readahead' to the threshold in an attempt to increase cutting
+ // speed; it's a tradeoff -- speed vs RAM-used.
+ if (totwritten > MEGABYTE(32) + readahead) {
+ //fdatasync(fd);
+ off_t headdrop = min(curpos - totwritten, totwritten * 2L);
+ posix_fadvise(fd, curpos - totwritten - headdrop, totwritten + headdrop, POSIX_FADV_DONTNEED);
+ totwritten = 0;
+ }
}
}
#endif
diff --git a/tools.h b/tools.h
index 7e57744b..bd2e97ce 100644
--- a/tools.h
+++ b/tools.h
@@ -4,7 +4,7 @@
* See the main source file 'vdr.c' for copyright information and
* how to reach the author.
*
- * $Id: tools.h 1.90 2006/01/15 16:19:56 kls Exp $
+ * $Id: tools.h 1.91 2006/02/04 13:58:01 kls Exp $
*/
#ifndef __TOOLS_H
@@ -242,15 +242,22 @@ public:
class cUnbufferedFile {
private:
int fd;
+ off_t curpos;
+ off_t cachedstart;
+ off_t cachedend;
off_t begin;
- off_t end;
+ off_t lastpos;
off_t ahead;
- ssize_t written;
+ size_t readahead;
+ size_t written;
+ size_t totwritten;
public:
cUnbufferedFile(void);
~cUnbufferedFile();
int Open(const char *FileName, int Flags, mode_t Mode = DEFFILEMODE);
int Close(void);
+ void SetReadAhead(size_t ra);
+ int FadviseDrop(off_t Offset, off_t Len);
off_t Seek(off_t Offset, int Whence);
ssize_t Read(void *Data, size_t Size);
ssize_t Write(const void *Data, size_t Size);
--
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