[PATCH] ARM: lib: use LDRD/STRD for data copy
Russell King - ARM Linux
linux at arm.linux.org.uk
Mon Mar 19 11:41:23 EDT 2012
On Mon, Mar 19, 2012 at 09:36:41AM -0500, Rob Herring wrote:
> On 03/19/2012 03:55 AM, Russell King - ARM Linux wrote:
> > On Mon, Mar 19, 2012 at 04:02:48PM +0900, Boojin Kim wrote:
> >> This patch uses LDRD/STRD that loads and stores data as DWORD unit
> >> for the copy of 8-words data.
> >> It brings better performance than LDRM/STRM that was used originally.
> > And what about CPUs that don't have ldrd/strd ?
> And what about CPUs that do have ldrd/strd but is slower than ldm/stm?
> I'm pretty sure that is almost everything currently out there.
The double-word load/stores were introduced in ARMv6. Some Intel based
CPUs prior to this have the support as well. Everything else doesn't.
So taht's nowhere close to 'almost everything'.
More information about the linux-arm-kernel