Re: [PATCH] fs: fput() can be called from interrupt context

From: Davide Libenzi
Date: Sat Mar 14 2009 - 10:33:44 EST


On Sat, 14 Mar 2009, Trond Myklebust wrote:

> > Did I miss something? This wouldn't be (eventually) on keventd shoulders,
> > but on aio work queue (aio_wq).
> > I guess we could do the same optimization we're already doing for ki_filp,
> > for ki_eventfd ...
>
> Last I checked, a call to schedule_work(&fddef->wq) would still run
> fd_defer_queue() under keventd.

Oh, you were commenting about Eric's patch-set. I thought you were talking
about the current status (that my reply to Andrew was hinting to), and was
wondering for a while from where fd_defer_queue() came from.



> That said, even if you were to run it under aio_wq, the argument remains
> the same: do you really want to add potentially long lasting sleeps onto
> a work queue that was designed to service fast i/o requests?

No, and if you roll back, you couldn't miss to notice that mine was a
question about the f_count direct manipulation/optimization. We can do the
same optimization for eventfd, although both will fall in the aio kthread
in any case, if we're holding the last insteance of the file* (that I
guess we can consider an unlikely case).
Dunno how worth it could be adding a new NCPU*thread(s) just to handle
delayed fputs.


- Davide


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