Andreas Holzhammer - GMX wrote:
> I'm using a diskless VDR 1.3.38 and noticed that during recordings the
> network is saturated for 1-2 seconds every 30 seconds. I haven't seen
> this with 1.3.22, so I asume this might be related to the
> cUnbufferedFile class in 1.3.35+.
>
> This leads to very uneven load on the vdr client (and the NFS-Server),
> where I've seen 10000 interrupts per second during the flushes (a few
> hundred irqs in between). I'm not sure whether this contributes to some
> of my recordings being broken (c*Repacker errors), but I'd like to
> distribute the writes more evenly.
>
> Is there a way to get cUnbufferedFile to write the data every second, er
> even continuously? The NFS-server is going to take care of writing the
> data to disk anyway.
the attached patch makes vdr behave.
i did this for the reasons you mention above; haven't seen any repacker errors
though (neither w/ or w/o the patch).
-------------- next part --------------
--- vdr-1.3.39.org/config.c 2006-01-13 15:19:37.000000000 +0000
+++ vdr-1.3.39/config.c 2006-01-15 18:31:51.000000000 +0000
@@ -424,6 +424,7 @@ 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);
@@ -491,6 +492,7 @@ 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-1.3.39.org/config.h 2006-01-13 15:17:19.000000000 +0000
+++ vdr-1.3.39/config.h 2006-01-15 18:31:51.000000000 +0000
@@ -231,6 +231,7 @@ public:
int UseSmallFont;
int MaxVideoFileSize;
int SplitEditedFiles;
+ int WriteStrategy;
int MinEventTimeout, MinUserInactivity;
int MultiSpeedMode;
int ShowReplayMode;
--- vdr-1.3.39.org/cutter.c 2005-10-31 12:26:44.000000000 +0000
+++ vdr-1.3.39/cutter.c 2006-01-15 18:31:51.000000000 +0000
@@ -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) {
@@ -118,10 +121,11 @@ void cCuttingThread::Action(void)
break;
if (FileSize > MEGABYTE(Setup.MaxVideoFileSize)) {
toFile = toFileName->NextFile();
- if (toFile < 0) {
+ if (!toFile) {
error = "toFile 1";
break;
}
+ toFile->setreadahead(MEGABYTE(20));
FileSize = 0;
}
LastIFrame = 0;
@@ -158,10 +162,11 @@ void cCuttingThread::Action(void)
cutIn = true;
if (Setup.SplitEditedFiles) {
toFile = toFileName->NextFile();
- if (toFile < 0) {
+ if (!toFile) {
error = "toFile 2";
break;
}
+ toFile->setreadahead(MEGABYTE(20));
FileSize = 0;
}
}
--- vdr-1.3.39.org/menu.c 2006-01-15 15:02:36.000000000 +0000
+++ vdr-1.3.39/menu.c 2006-01-15 18:31:51.000000000 +0000
@@ -2529,6 +2529,7 @@ 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-1.3.39.org/tools.c 2006-01-15 14:31:45.000000000 +0000
+++ vdr-1.3.39/tools.c 2006-01-15 18:31:51.000000000 +0000
@@ -7,6 +7,7 @@
* $Id: tools.c 1.110 2006/01/15 14:31:45 kls Exp $
*/
+#include "config.h"
#include "tools.h"
#include <ctype.h>
#include <dirent.h>
@@ -1040,11 +1041,12 @@ 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)
+#define usefadvise() (Setup.WriteStrategy!=1)
+
cUnbufferedFile::cUnbufferedFile(void)
{
fd = -1;
@@ -1059,8 +1061,18 @@ 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 (usefadvise())
+ posix_fadvise(fd, 0, 0, POSIX_FADV_RANDOM);
+ }
return fd;
}
@@ -1068,15 +1080,10 @@ 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;
+ 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);
+ begin = lastpos = ahead = 0;
written = 0;
}
#endif
@@ -1085,45 +1092,98 @@ int cUnbufferedFile::Close(void)
return close(OldFd);
}
-off_t cUnbufferedFile::Seek(off_t Offset, int Whence)
-{
- if (fd >= 0)
- return lseek(fd, Offset, Whence);
- return -1;
-}
-
+// 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 this 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)
+
+#define KREADAHEAD MEGABYTE(4) // amount of kernel/fs prefetch that could
+ // happen in addition to our own.
+#define FADVGRAN 4096 // AKA fadvise-chunk-size; PAGE_SIZE or
+ // getpagesize(2) would also work.
+
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 (jumped) { // ie some kind of jump happened.
+ pendingreadahead += ahead-lastpos+KREADAHEAD;
+ // 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)
+ if (lastpos > (ahead+KREADAHEAD))
+ lastpos = ahead+KREADAHEAD;
+ }
+ // jumped backward? - drop both last read _and_ read-ahead
+ else
+ if (curpos < begin)
+ lastpos = ahead+KREADAHEAD;
+ // jumped backward, but still inside prev read window? - pretend we read less.
+ else /* if (curpos >= begin) */
+ lastpos = curpos;
+ }
+
#endif
ssize_t bytesRead = safe_read(fd, Data, Size);
#ifdef USE_FADVISE
+ // Now drop data accessed during _previous_ Read(). (ie. begin...lastpos)
+ // fadvise() internally has page granularity; it drops only whole pages
+ // from the range we specify (since it cannot know if we will be accessing
+ // the rest). This is why we drop only the previously read data, and do it
+ // _after_ the current read() call, while rounding up the window to make
+ // sure that even not PAGE_SIZE-aligned data gets freed.
+ // Try to merge the fadvise calls a bit in order to reduce overhead.
+ if (usefadvise() && 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-(FADVGRAN-1), lastpos-begin+(FADVGRAN-1)*2, POSIX_FADV_DONTNEED);
+ begin = curpos;
+ }
+
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;
+ //dsyslog("jump: %06ld ra: %06ld size: %ld", jumped, (long)readahead, (long)Size);
+
+ // no jump? (allow small forward jump still inside readahead window).
+ if (usefadvise() && jumped>=0 && jumped<=(off_t)readahead) {
+ // Trigger the readahead IO, but only if we've used at least
+ // 1/4 of the previously requested area. This avoids calling
+ // fadvise() after every read() call.
+ //if (ahead<(off_t)(curpos+readahead/2)) {
+ if ((ahead-curpos)<(off_t)(readahead-readahead/4)) {
+ posix_fadvise(fd, curpos, readahead, POSIX_FADV_WILLNEED);
+ ahead = curpos + readahead;
+ }
+ if ( readahead < Size*64 ) { // automagically tune readahead size.
+ readahead = Size*64;
+ //dsyslog("Readahead for fd: %d increased to %ld", fd, (long)readahead);
+ }
+ }
+ else {
+ // jumped - we really don't want any readahead now. otherwise
+ // eg fast-rewind gets in trouble.
+ //ahead = curpos;
+ // let's try a little readahead...
+ posix_fadvise(fd, curpos, KILOBYTE(32), POSIX_FADV_WILLNEED);
+ ahead = curpos + KILOBYTE(32);
+
+ // Every now and then, flush all cached data from this file; mostly
+ // to get rid of nonflushed readahead coming from _previous_ jumps
+ // (if the readahead I/O hasn't finished by the time we called
+ // fadvice() to undo it, the data could still be cached).
+ // The accounting does not have to be 100% accurate, as long as
+ // this triggers after _some_ jumps we should be ok.
+ if (usefadvise() && pendingreadahead>MEGABYTE(40)) {
+ pendingreadahead = 0;
+ posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+ }
+ }
}
- else
- end = pos;
+ lastpos = curpos;
#endif
return bytesRead;
}
@@ -1132,29 +1192,37 @@ ssize_t cUnbufferedFile::Read(void *Data
ssize_t cUnbufferedFile::Write(const void *Data, size_t Size)
{
+ //dsyslog("Unbuffered:Write: fd: %d %8ld..%8ld size: %5ld", fd, curpos, curpos+Size, (long)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;
+ //dsyslog("flush buffer: %d (%d bytes, %ld-%ld)", fd, written, begin, lastpos);
+ if (usefadvise() && 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-4095);
+ 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 (usefadvise() && 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
--- vdr-1.3.39.org/tools.h 2006-01-08 11:40:37.000000000 +0000
+++ vdr-1.3.39/tools.h 2006-01-26 21:02:24.000000000 +0000
@@ -237,22 +237,40 @@ public:
/// cUnbufferedFile is used for large files that are mainly written or read
/// in a streaming manner, and thus should not be cached.
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
class cUnbufferedFile {
private:
int fd;
+ off_t curpos;
off_t begin;
- off_t end;
+ off_t lastpos;
off_t ahead;
- ssize_t written;
+ size_t pendingreadahead;
+ 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);
- off_t Seek(off_t Offset, int Whence);
+ off_t Seek(off_t Offset, int Whence)
+ {
+ //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;
+ }
+
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 {
