vdev_geom_io: parallelize ?

[Pawel Jakub Dawidek]

On Fri, Apr 23, 2010 at 01:04:50AM +0300, Andriy Gapon wrote:
> 
> Just thinking out loud.
> 
> Currently ZFS vdev_geom_io does something like:
> for (...) {
> 	...
> 	g_io_request(...);
> 	biowait(...);
> 	...
> }
> I/O is done in MAXPHYS chunks.
> 
> If that was changed to first issuing all the requests and only after that
> waiting on them, could there be any performance benefit?
> Or cases of vdev_geom_io with size > MAXPHYS are too rare?
> Or something else?

The vdev_geom_io() function is there only to read ZFS labels, it is not
used during regular I/O. Regular I/O requests are handled asynchronously
by the vdev_geom_io_start() function.

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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