On Mon, Jan 21, 2019 at 11:30:02AM +0530, Pramod Kumar wrote:Accelerator
On Mon, Jan 21, 2019 at 11:28 AM Pramod Kumar <pramod.kumar@xxxxxxxxxxxx>In this example is Linux running on the server, or on the accelerator?
wrote:
Need comes from a specific use case where one Accelerator card(SoC) is
plugged in a sever over a PCIe interface. This Card gets supply from a
battery, which could provide very less power for a very small time, in case
of any power loss. Once Card switches to battery, this has to reduce its
power consumption to its lowest point and back-up the DDR contents asap
before battery gets fully drained off.
Data in DDR is being written to disk at this time (disk is connected to accelerator)
What precisely are you trying to back up from DDR, and why?
What is responsible for backing up that contents?
Since battery can provide limited power for a very short time hence need toIf you're stopping CPUs from completely arbitrary states, what is the
transition to lowest power. As per the transition process , CPUs power
domain has to be off but before that it needs to flush out its content to
system memory(L3) so that content could be backed-up by a MCU, a controller
consuming very less power. Since we can not afford plugging-out every
individual CPUs in sequence hence uses ipi_cpu_stop for all other CPUs
which ultimately switch to ATF to flush out all the CPUs caches and comes
out of coherency domain so that its power rails could be switched-off.
benefit of saving the RAM contents?
CPUs might be running with IRQs disabled for an arbitrarily long time,
so there's no guarantee that all of them will be turned off before power
is lost.
I'm very confused as to what you're trying to achieve here.
Thanks,
Mark.