Re: checkpoint writeback via sync_file_range

On Wed, Jan 11, 2012 at 9:28 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:

> It does open the door to various other uses, so I think this work will
> be useful.

Yes, I think this would allow a better design for the checkpointer.

Checkpoint scan will collect buffers to write for checkpoint and sort
them by fileid, like Koichi/Itagaki already suggested.

We then do all the writes for a particular file, then issue a
background sync_file_range, then sleep a little. Loop. At end of loop,
collect up and close the sync_file_range calls with a
SYNC_FILE_RANGE_WAIT_AFTER.

So we're interleaving the writes and fsyncs throughout the whole
checkpoint, not bursting the fsyncs at the end.

With that design we would just have a continuous checkpoint, rather
than having 0,5 or 0.9

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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