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mem: Use beats_per_clock as the DDR data rate for DRAMPower

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The data rate is used by the drampower lib to estimate the power
consumption of the DRAM Core. Previously, we used the formula:

burst_cycles = divCeil(p->tBURST_MAX, p->tCK);
data_rate = p->burst_length / burst_cycles;

to derive the data_rate. However, under certain configurations this
formula computes the wrong result due to rounding errors. This patch
simplifies the way we derive the data_rate by passing the value of the
DRAM parameter beats_per_clock.

Change-Id: Ic8cd35bb4641d9c0a704675d2672a6fe4f4ec13e
Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Wendy Elsasser <wendy.elsasser@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30056
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
This commit is contained in:
Nikos Nikoleris
2020-05-19 17:25:32 +01:00
parent 0bd936d071
commit e50ab5a2ec
2 changed files with 1 additions and 17 deletions
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13
src/mem/drampower.cc
View File

@@ -53,7 +53,7 @@ DRAMPower::getArchParams(const DRAMCtrlParams* p)
archSpec.nbrOfBanks = p->banks_per_rank;
// One DRAMPower instance per rank, hence set this to 1
archSpec.nbrOfRanks = 1;
archSpec.dataRate = getDataRate(p);
archSpec.dataRate = p->beats_per_clock;
// For now we can ignore the number of columns and rows as they
// are not used in the power calculation.
archSpec.nbrOfColumns = 0;
@@ -146,14 +146,3 @@ DRAMPower::hasTwoVDD(const DRAMCtrlParams* p)
{
return p->VDD2 == 0 ? false : true;
}
uint8_t
DRAMPower::getDataRate(const DRAMCtrlParams* p)
{
uint32_t burst_cycles = divCeil(p->tBURST_MAX, p->tCK);
uint8_t data_rate = p->burst_length / burst_cycles;
// 4 for GDDR5
if (data_rate != 1 && data_rate != 2 && data_rate != 4 && data_rate != 8)
fatal("Got unexpected data rate %d, should be 1 or 2 or 4 or 8\n");
return data_rate;
}

5
src/mem/drampower.hh
View File

@@ -73,11 +73,6 @@ class DRAMPower
*/
static Data::MemPowerSpec getPowerParams(const DRAMCtrlParams* p);
/**
* Determine data rate, either one or two.
*/
static uint8_t getDataRate(const DRAMCtrlParams* p);
/**
* Determine if DRAM has two voltage domains (or one)
*/