Re: [PATCH 58/71] xfs: garbage collect old cowextsz reservations

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Mon, Sep 26, 2016 at 02:52:09PM -0700, Darrick J. Wong wrote:
> The two functions /could/ be merged but I'm hesitant to combine them
> because they run as different workqueue items.
> 
> Setting speculative_cow_prealloc_lifetime to a (much) higher value than
> speculative_prealloc_lifetime has been useful for combatting CoW
> fragmentation on VM hosts where the VMs experience bursty write
> behaviors and we can keep the utilization ratios low enough that we
> don't start to run out of space.  IOWs, it benefits us to keep the CoW
> fork reservations around for as long as we can unless we run out of
> blocks or hit inode reclaim.

Ok, so there is a good use case for it.  It just felt to me like
there was a little bit too much duplication, that's why I asked.