[SLOF] [PATCH 3/4] fbuffer: Implement MRMOVE as an accelerated primitive

Nikunj A Dadhania nikunj at linux.vnet.ibm.com
Wed Sep 9 16:45:24 AEST 2015

Thomas Huth <thuth at redhat.com> writes:

> On 03/08/15 17:53, Thomas Huth wrote:
>> On 03/08/15 12:37, Nikunj A Dadhania wrote:
>>> Thomas Huth <thuth at redhat.com> writes:
>>>> The character drawing function fb8-draw-character uses "mrmove"
>>>> (which moves main memory contents to IO memory) to copy the data
>>>> of the character from main memory to the frame buffer. However,
>>>> the current implementation of "mrmove"  performs quite badly on
>>>> board-qemu since it triggers a hypercall for each memory access
>>>> (e.g. for each 8 bytes that are transfered).
>>>> But since the KVMPPC_H_LOGICAL_MEMOP hypercall can transfer bigger
>>>> regions at once, we can accelerate the character drawing quite a
>>>> bit by simply mapping the "mrmove" to the same macro that is
>>>> already used for the "rmove". For keeping board-js2x in sync,
>>>> this patch also transforms the "mrmove" for js2x into primitives.
>>>> Signed-off-by: Thomas Huth <thuth at redhat.com>
>>> I dont have a js2x handy, did you test this on js2x?
>> No, sorry, unfortunately, I also was not able to test this on js2x yet.
>> I still have a YDL PowerStation somewhere in a corner of my flat, but
>> it's currently not set up ... will do that one day when I got enough
>> spare time again, but that won't happen within the next few weeks (KVM
>> forum's ahead!). So if there are problems, I'll fix them up as soon as I
>> got the PowerStation running again (and I guess there might be other
>> problems, too, since board-js2x hardly got any testing within the last
>> months/years, I think).
> FWIW, I've recently dusted off my PowerStation and gave it a try...
> the HEAD of the SLOF master branch is unfortunately quite broken on js2x
> nowadays (I'll try to send some first fixes later), but I was able to
> cherry-pick the fbuffer acceleration patches to an older level of SLOF
> from 2012 which was still working nicely.

TCG seem to be broken with this new series, git bisect pointed to:

59a135e fbuffer: Implement MRMOVE as an accelerated primitive

I havent looked into detail of why its failing though.


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