[mythtv] [mythtv-commits] mythtv commit: r23435 - in trunk/mythtv by mdean

Stuart Auchterlonie stuarta at squashedfrog.net
Fri Feb 5 16:59:07 UTC 2010


On 04/02/2010 16:46, Yeechang Lee wrote:
> Daniel Kristjansson<danielk at cuymedia.net>  says:
>> We want deletes to take less than 0.01 seconds but can tolerate 0.04
>> to 0.21 seconds depending on other factors.
>
> May I again suggest, then, considering adjusting upward the stock
> ThreadedBufferWriter buffer sizes? Or (WARNING: Configuration setting
> feature request incoming) permitting their adjustment outside
> compilation?
>
> While the 0.22 writer's performance is *greatly* improved, I still
> find that something like
>
> -const uint ThreadedFileWriter::TFW_DEF_BUF_SIZE   = 2*1024*1024;
> -const uint ThreadedFileWriter::TFW_MAX_WRITE_SIZE = TFW_DEF_BUF_SIZE / 4;
> -const uint ThreadedFileWriter::TFW_MIN_WRITE_SIZE = TFW_DEF_BUF_SIZE / 32;
> +const uint ThreadedFileWriter::TFW_DEF_BUF_SIZE   = 64*1024*1024;
> +const uint ThreadedFileWriter::TFW_MAX_WRITE_SIZE = TFW_DEF_BUF_SIZE / 32;
> +const uint ThreadedFileWriter::TFW_MIN_WRITE_SIZE = TFW_DEF_BUF_SIZE / 256;
>
> is required to ensure that FireWire (not ATSC) recordings' lengths are
> consistently (recording time - 5 seconds  1 second) versus (recording
> time - 30 seconds  15 seconds) without the patch.
>
> (I have empirically tested 64 to see whether it is the optimal value
> for my JFS-based RAID arrays, but a larger value than 2 definitely
> is. From 0.18 to 0.21 I had to use something akin to
>
> +const uint ThreadedFileWriter::TFW_DEF_BUF_SIZE   = 256*1024*1024;
> +const uint ThreadedFileWriter::TFW_MAX_WRITE_SIZE = TFW_DEF_BUF_SIZE / 128;
> +const uint ThreadedFileWriter::TFW_MIN_WRITE_SIZE = TFW_DEF_BUF_SIZE / 1024;
>
> for the same results, and the writer was still not nearly as resilient
> as it is now.)
>

I'd be curious to see how the new lockless threaded file writer would
work for you. I intend to put it in for 0.24...

http://svn.mythtv.org/trac/ticket/6330

Stuart



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