Re: [PATCHv2 11/11] writeback: prevent unnecessary bdi threadswakeups

From: Artem Bityutskiy
Date: Wed Jul 21 2010 - 07:52:56 EST


On Wed, 2010-07-21 at 12:31 +0300, Artem Bityutskiy wrote:
> spin_unlock(&inode_lock);
> +
> + if (wakeup_bdi) {
> + spin_lock(&bdi->wb_lock);
> + if (!bdi->wb.task)
> + wake_up_process(default_backing_dev_info.wb.task);
> + else
> + wake_up_process(bdi->wb.task);
> + spin_unlock(&bdi->wb_lock);
> + }
> }

Dave,

I do not know whether this stuff will end up in upstream, I did not get
any feed back from Jens so far. But if it will, I'd like to let you know
that the code quoted above is similar to the 'bdi_queue_work()'
function. And the purpose is very similar. But you added a
'trace_writeback_nothread()' call to 'bdi_queue_work()', and I think a
similar call has to be here.

Can I call 'trace_writeback_nothread()'? I guess not. Should I create
another trace point? Any hints/instructions?

Note, the patches are against Jens' tree.

Please, see linux-fsdevel or lkml for the full patch and its purposes.

--
Best Regards,
Artem Bityutskiy (ÐÑÑÑÐ ÐÐÑÑÑÐÐÐ)

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