Rik van Riel wrote:
Just for fun, could you also try measuring how long it takesThe original code did the read back as well, I stripped it out to make the code smaller to post.
to read back the files in question ?
Both individually and in parallel...
It was the read back performance that I was most interested in. I found that ext2/3 interleave all the blocks on the disk. With 2 stream the read performance is 50%, 4 streams give 25% etc.
I have one really bad case where I record a TV stream at 500kByte/s + a radio one at 25kByte/s. These blocks are interleaved on the disk and the read performance of the radio stream is reduced by the data ratio, i.e. 1:20, so I get a miserable read performance of ~ 1MB/s.
I found that ext2, ext3 and Reiserfs behave similarly.
XFS and JFS appear to coalesce the data blocks during the write phase and can read the data back at near maximum performance.
Jon
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/