[PATCH 3/5]: ipr: kexec boot speed improvements

Anton Blanchard anton at samba.org
Sun Nov 30 12:43:19 PST 2014

Hi Brian,

> > Currently when performing a kexec boot with an ipr adapter,
> > the adapter gets shutdown completely, flushing all write
> > cache, as well as performing a full hardware reset of the card
> > during the shutdown phase of the old kernel. This forces
> > the new kernel to then wait for the adapter firmware to
> > reinitialize, which slows down kexec boot. There is no
> > need to do all of this on the newer ipr adapters, since they
> > support the ability to cancel outstanding error buffers.
> > 
> > This patch adds a special case for kexec boot to simply
> > cancel these outstanding error buffers, and as long as
> > there is no other I/O outstanding to the adapter, which
> > there shouldn't be, place the adapter into a state
> > where it has no memory of any DMA addresses from the old
> > kernel, then disable the device. This significantly
> > speeds up kexec boot, particularly in configurations with
> > multiple ipr adapters.
> > 
> > Signed-off-by: Brian King <brking at linux.vnet.ibm.com>
> > ---
> This reduces boot time on my box from 80 seconds to 34 seconds. ppc64
> kernel developers (who boot boxes continually) thank you!
> Tested-by: Anton Blanchard <anton at samba.org>

Just checking on this series. I'm very keen to see it go in since it is
a huge improvement in boot time.


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