On 10/25/2011 02:48 AM, Ohad Ben-Cohen wrote:
Modern SoCs typically employ a central symmetric multiprocessing (SMP)
application processor running Linux, with several other asymmetric
multiprocessing (AMP) heterogeneous processors running different instances
of operating system, whether Linux or any other flavor of real-time OS.
OMAP4, for example, has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP.
Typically, the dual cortex-A9 is running Linux in a SMP configuration, and
each of the other three cores (two M3 cores and a DSP) is running its own
instance of RTOS in an AMP configuration.
AMP remote processors typically employ dedicated DSP codecs and multimedia
hardware accelerators, and therefore are often used to offload cpu-intensive
multimedia tasks from the main application processor. They could also be
used to control latency-sensitive sensors, drive 'random' hardware blocks,
or just perform background tasks while the main CPU is idling.
I understand that I might be saying this pretty late in the review, but
can we please stop calling these as AMP configurations? IMHO, in the
kernel, we should limit the terms AMP and SMP to be based on the
processors/CPUs on which this specific instance of the Linux kernel can
schedule processes on.
With the definition of AMP that you are trying to use, even a Intel
386/486 machine with just one Intel core will be an AMP system. I'm sure
even those old PCs had other processors inside other devices (HDDs,
GPUs, etc) executing random firmware.
So, what would you call Intel dual core machines? SMP-AMP? Your proposed
use of AMP muddles these terms and makes them useless. I think AMP
should be reserved for things like the ARM Big-little architecture, etc,
where the CPUs in which the kernel schedules processes are not identical.
Sorry for the rant, this naming just rubs me the wrong way. I definitely
appreciate the idea behind these patches.
Thanks,
Saravana
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