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Re: [Xen-devel] reasons/requirements for some of patches/linux-*

  • To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
  • From: "Andrew Warfield" <andrew.warfield@xxxxxxxxxxxx>
  • Date: Fri, 6 Oct 2006 18:08:10 -0700
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Andrew Warfield <andy@xxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx>
  • Delivery-date: Fri, 06 Oct 2006 18:08:35 -0700
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

> Could anyone give a description (and reason it is needed for Xen, if that's
> not obvious from the description) for each of
> blktap-aio-16_03_06.patch

Not sure. Andrew Warfield or Julian Chesterfield probably will know. I would
guess it's probably a backport of AIO changes from a more recent kernel, but
I'm not certain about that.

The patch allows polling of aio and non-aio file descriptors through a
single call.  It's a stopgap that was sent to the aio devel list and
is there in anticipation of a solution for mixed polling in linux.

The old approach was to have a separate thread to call aio_getevents
and signal that to the main poll loop through a pipe -- it's no less
ugly, but keeps changes to user space at a cost in performance.


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