[mythtv-users] Auto-expire two files while recording two files causing IOBOUND block.

[Steve Bower]

>>>>> "BG" == Blues Guy <bluesguy_1 at yahoo.com> writes:

BG> I have my Myth box setup to record Letterman and Leno, and also to
BG> only keep the 2 most recent shows of each.  So when it starts
BG> recording the two shows, it detects that it can expire the oldest
BG> two.  So now, it's writing two MPEG-2 files from the PVR's, while
BG> deleting two large MPEG-2 files from the drive and this causes
BG> blocking every night, consistently and repeatably.  (and somewhat
BG> understandably).  So my question is, is there anyway to either run
BG> the expire process at a later time, or at a lower priority to solve
BG> this?

BG> The only other thing I can think of doing, is that I'm using ext3
BG> and I forgot to use the "-T largefile4" to tune the block size from
BG> the default, so maybe the increased inode count is giving it fits on
BG> what is essentially four 2GB files being worked at the same time?  I
BG> created a separate partition for /mnt/store so fixing this would be
BG> pretty simple if it would help.

ext2 and ext3 seem to go through a LOT of I/O when you delete large
files.  I suspect this is from rewriting the block allocation list (or
is it a bitmap?  I forget!).

I switched to jfs on my video directory for just that reason.  Now
deleting 8G HDTV files takes a second or three, instead of 30.

If you're planning on moving to a whole new partition anyways, give jfs
a shot.  Testing it with dd and rm should be easy enough!

  Steve.


BG> Does anyone have firsthand experience with this
BG> parameter to know how much of a differnce it makes, or
BG> have a similar scheduling situation, but without the
BG> IOBOUND problem?

BG> For the record, the system is a Pundit, PVR-250 &
BG> PVR-350, 2GHz Celery (running at 2.6GHz), 512MB, 200GB
BG> 7200RPM Western Digital HDD.

BG> The evidence from the backend log :'>

BG> 2004-01-29 23:35:02 Started recording "Late Show With
BG> David Letterman" on channel: 1002 on cardid: 1,
BG> sourceid 1
BG> 2004-01-29 23:35:02 Started recording "The Tonight
BG> Show With Jay Leno" on channel: 1005 on cardid: 2,
BG> sourceid 1
BG> 2004-01-29 23:35:02 Changing from None to
BG> RecordingOnly
BG> 2004-01-29 23:35:02 Changing from None to
BG> RecordingOnly
BG> 2004-01-29 23:44:44 Expiring "Late Show With David
BG> Letterman" from 2004-01-27T23:35:00, too many
BG> episodes.
BG> 2004-01-29 23:44:47 Expiring "The Tonight Show With
BG> Jay Leno" from 2004-01-27T23:35:00, too many episodes.
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriterIOBOUND -
BG> blocking in ThreadedFileWriter::Write()
BG> ::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> IOBOUND - blocking in ThreadedFileWriter::Write()
BG> 2004-01-30 00:00:01 Found changes in the todo list.