On 02/01/2012 12:26 AM, Tao Ma wrote:
Hi Allison,
On 02/01/2012 06:33 AM, Allison Henderson wrote:
Hi Yongqiang,
I've have been working on an extent lock implementation that uses an
rbtree to keep track of locked extents, and I think I will probably end
up with a something similar to the tree that you've already set up for
delayed extents. So I wanted to send a note out to see what folks would
think about the idea of merging the two solutions.
If we did this, the tree would get a little more complex in that it
would have to keep track of more than just delayed extents. It would
have to keep track of all extents and the processes that are waiting on
them. So I guess it would kind of turn into an extent status tree. I
also realize that some folks wanted to see range locks go into /lib as
general purpose code so that other filesystems or kernel code could use
it too, but the advantage to this approach would be one less tree for
ext4 to keep track of. Any thoughts?
We (Taobao) are very interested in this stuff and it should benefit
several of our workload(It is on our todo list for a long time). I guess
Yongqiang's solution is a little bit limited to the only delayed extent
case, and your new solution at least has 2 more benefits:
1. improve the direct i/o read/write
2. speed up the extent search since now we only cache one in
ei_cached_extent.
So please go ahead with your new solution. btw, do you have any timeline
for it? We are glad to provide any help if needed.
Thanks
Tao
Thx all for the feed back, it sounds like there will be a lot of
benefits to extending Yongqiang's delayed extent tree, so I will work on
a solution based on that patch set. Unfortunately though, I cannot give
a time frame for this work item at the moment. There are currently some
other business needs that may take priority over this one, and until
those have been decided, I cannot make any promises at this point in
time. But I will work as quickly as I can with it since it is currently
on my plate, and I will keep folks updated. At the moment, feed back
and guidance is most helpful to me. Also, since the delayed extent
solution is now a dependency for my solution, anything to help get that
reviewed and merged would help me too. Yongqiang, does the set still
need review? I think I recall Ted saying it was still on his list of
things to look at. Im sure I will give it some good exercise here too.
Thx all for your help! :)
Allison Henderson
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