[PATCH 1/1] Add config option for batched hcalls
will_schmidt at vnet.ibm.com
Tue Sep 28 06:06:46 EST 2010
On Sat, 2010-09-25 at 22:49 -0500, Olof Johansson wrote:
> On Fri, Sep 24, 2010 at 04:44:15PM -0500, Will Schmidt wrote:
> > Add a config option for the (batched) MULTITCE and BULK_REMOVE h-calls.
> > By default, these options are on and are beneficial for performance and
> > throughput reasons. If disabled, the code will fall back to using less
> > optimal TCE and REMOVE hcalls. The ability to easily disable these
> > options is useful for some of the PREEMPT_RT related investigation and
> > work occurring on Power.
> I can see why it's useful to enable and disable, but these are all
> runtime-checked, wouldn't it be more useful to add a bootarg to handle
> it instead of adding some new config options that pretty much everyone
> will always go with the defaults on?
> The bits are set early, but from looking at where they're used, there
> doesn't seem to be any harm in disabling them later on when a bootarg
> is convenient to parse and deal with?
> It has the benefit of easier on/off testing, if that has any value for
> production debug down the road.
Thats a good idea, let me poke at this a bit more, see if I can get
bootargs for this.
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