[Btrfs-devel] [RFC] All my fsync changes

[Josef Bacik]

On Thu, Aug 09, 2007 at 07:49:10PM -0400, Chris Mason wrote:
> On Thu, 9 Aug 2007 17:56:18 -0400
> Josef Bacik <jwhiter at redhat.com> wrote:
> 
> > Hello,
> > 
> > Ok here are all my fsync changes, including the fix for the
> > put_transaction stuff that I posted earlier.  I figure it'll be
> > easier to just commit it as one thing then each individual peice.
> > The additional thing that I did was add a radix tree that tracks the
> > current outstanding transactions.  I also added a field to the in
> > memory btrfs inode that keeps track of the last transaction that
> > modified the inode.  So when we go to do a fsync on the inode if the
> > commit was already done or the transaction was removed (meaning it
> > had been committed and freed) we just exit out.  So here are the
> > numbers. This is running fs_mark with the following command
> > 
> > fs_mark -d /mnt/btrfs-test/default/ -s 10240 -n 1000
> > 
> > run 10 times.  First run is without any of the patches, with the
> > exception of the put_transaction/trans_mutex fix.
> > 
> > AVG: 61 files/sec
> > 
> > And this is the numbers with the patch thats attached to this email
> > 
> > 
> > AVG: 94.32 files/sec
> 
> Great, although I'm a little surprised it helps so much for a single
> thread case.
> 
> > 
> > Now I'm kind of uncertain about how I track the last_trans for the
> > inode, I think its right but I'm not entirely sure, so if I need to
> > be doing this elsewhere please let me know.  Thanks much,
> 
> This code really looks correct, one change I would suggest is that
> since the transactions are put down in order, we don't have to worry
> about maintaining the radix tree.  You know that if transid Y is on
> disk, then transid Y-1 and Y-2 etc are also on disk.
> 
> So, you can just record the most recent transid to hit the disk and
> compare it with the id you store in the inode, forcing a commit if
> your transaction isn't on disk yet. Did you need the radix tree for
> something else?
>

Nope I just had it in my original notes so I figured you wanted to use it for
something else on down the line.  I'll rip it out and do it the easy way
tomorrow :).  Thanks much,

Josef