Hi.
I can't find any mention of this elsewhere, so I would like to report
this as a bug - or may be an expected result, just not documented
anywhere (?).
I have found that a large exclude-from=file negatively affects the speed
of tar.
This dataset consists of about 2,4 million files, and is 468 GiB in size.
To test this, I made up a exclude-file of entries which would not match
anything in the dataset.
With 100 exclude-lines, I got a throughput of 461MiB/s.
With 50 exclude-lines, I got a throughput of 552MiB/s.
With 1 exclude-line, I got a throughput of 685MiB/s.
Without any exclude-from, I got 691MiB/s.
The result are not linear with the numbers of excludes, but it shows
that each exclude-line makes a negative impact on performance.
Does anyone have an explanation to this behaviour? We need to exclude
some of our data before writing it out to tape, but we don't want to
loose to much speed.
