On thu, 12 Sep 2013 19:37:18 +0200, David Sterba wrote:
On Thu, Sep 12, 2013 at 04:08:15PM +0800, Qu Wenruo wrote:
Use kernel workqueue and kernel workqueue based new btrfs_workqueue_struct to replace
the old btrfs_workers.
The main goal is to reduce the redundant codes(800 lines vs 200 lines) and
try to get benefits from the latest workqueue changes.
About the performance, the test suite I used is bonnie++,
and there seems no significant regression.
You're replacing a core infrastructure building block, more testing is
absolutely required, but using the available infrastructure is a good
move.
I found a few things that do not replace the current implementation
one-to-one:
* the thread names lost the btrfs- prefix, this makes it hard to
identify the processes and we want this, either debugging or
performance monitoring
* od high priority tasks were handled in threads with unchanged priority
and just prioritized within the queue
newly addded WQ_HIGHPRI elevates the nice level of the thread, ie.
it's not the same thing as before -- I need to look closer
* the idle_thresh attribute is not reflected in the new code, I don't
know if the kernel workqueues have something equivalent
Other random comments:
* you can use the same files for the new helpers, instead of bwq.[ch]
* btrfs_workqueue_struct can drop the _struct suffix
* WQ_MEM_RECLAIM for the scrub thread does not seem right
I think scrub_workers,scrub_wr_completion_workers still need WQ_MEM_RECLAIM.
However scrub_nocow_workers does not need WQ_MEM_RECLAIM flags.
Did you mean this?
If you didn't mean this, would you please tell me why the WQ_MEM_RECLAIM
is not
needed?
Thanks
Qu
* WQ_FREEZABLE should be probably set
david
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Qu Wenruo
Development Dept.I
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST)
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TEL: +86+25-86630566-8526
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