4.8 ffs_dirpref problem

Don Lewis truckman at FreeBSD.org
Fri Oct 31 11:13:42 PST 2003

On 31 Oct, Ken Marx wrote:
> Kirk McKusick wrote:
>> I know it takes a lot of time, but I would like to hear of the results
>> when you do the initial loading of the filesystem using Don's code as
>> that may well effect the set of choices that it has.
> Ok. I've done this using 48k avgfilesize, and 1500 filesperdir.
> I left our hashtable patch in.
> I can give details, but Don's code seems to average a healthy
> 64-5sec/1.5gb untar. I.e., basically equivalent to the 4.4 code.  But
> after 90% or so starts consuming more time - up to 90-130 seconds
> (system time). This increase is not always monotonic. Timings in
> the 60sec range to occur.  (I double-checked this, re-running
> starting at 97%.)
> The 4.4 dirpref code seems a bit better in this regime, staying
> mostly in the 60-70 sec range.

I suspect that the problem is caused by setting {minbfree,minifree} to
75% of {avgbfree,avgifree}, which is still allowing cylinder groups to
overflow even with my patch.  I'm somewhat hesitant to go to 100%, since
there may not be many cylinder groups with free blocks and inodes both
above average.

Can you send me the first part of the dumpfs output for this filesystem?

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