Re: Performance issue

Rik van Riel (
Tue, 7 Jul 1998 19:33:58 +0200 (CEST)

On Tue, 7 Jul 1998 wrote:

> I'm using a large scsi disk. The first part of the disk is raw used for large
> video chunks and on the second part of the disk is an ext2 filesystem. On this
> filesystem data is stored for the database.

Stupid answer: don't do this ;(

> Anybody an idea how to solve this problem?

Use two threads for the video app and make sure that the
'first' thread does enough readahead that the actual
video part already has the data in memory.

The second part is about tuning bdflush. It should be
allowed to:
- have loads of dirty buffers
- sync just a few (say 64) dirty buffers per turn, as
to not overwhelm the disk
- keep dirty buffers for a long time, since they might
be written to again before the 'long commit' has been
made -- sparing and I/O

Alternatively, you post to your local hardware newsgroup
and swap the large disk for two small ones :-)
This might not have the same amount of 'style', but it
will work just as effectively. I wonder if you will be
able to find a disk with less than 0.8MB/s throughput...

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