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traffic-control: (merges !120) More thorough testing of CoDel arithmetic

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This commit is contained in:
Tom Henderson
2019-10-11 06:51:35 -07:00
parent be11a079ce
commit 858dc55557
1 changed files with 25 additions and 30 deletions
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55
src/traffic-control/test/codel-queue-disc-test-suite.cc
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@@ -37,7 +37,7 @@ using namespace ns3;
/* needed shift to get a Q0.32 number from rec_inv_sqrt */
#define REC_INV_SQRT_SHIFT_ns3 (32 - REC_INV_SQRT_BITS_ns3)
static uint16_t _codel_Newton_step (uint32_t count, uint16_t rec_inv_sqrt)
static uint16_t _codel_Newton_step (uint16_t rec_inv_sqrt, uint32_t count)
{
uint32_t invsqrt = ((uint32_t)rec_inv_sqrt) << REC_INV_SQRT_SHIFT_ns3;
uint32_t invsqrt2 = ((uint64_t)invsqrt * invsqrt) >> 32;
@@ -337,23 +337,17 @@ CoDelQueueDiscNewtonStepTest::DoRun (void)
// Spot check a few points in the expected operational range of
// CoDelQueueDisc's m_count and m_recInvSqrt variables
uint32_t count = 2;
uint16_t recInvSqrt = 65535;
queue->m_count = count;
queue->m_recInvSqrt = recInvSqrt;
queue->NewtonStep ();
// Test that ns-3 value is exactly the same as the Linux value
NS_TEST_ASSERT_MSG_EQ (_codel_Newton_step (count, recInvSqrt), queue->m_recInvSqrt,
"ns-3 NewtonStep() fails to match Linux equivalent");
count = 4;
recInvSqrt = 36864;
queue->m_count = count;
queue->m_recInvSqrt = recInvSqrt;
queue->NewtonStep ();
// Test that ns-3 value is exactly the same as the Linux value
NS_TEST_ASSERT_MSG_EQ (_codel_Newton_step (count, recInvSqrt), queue->m_recInvSqrt,
uint16_t result;
for (uint16_t recInvSqrt = 0xff; recInvSqrt > 0; recInvSqrt /= 2)
{
for (uint32_t count = 1; count < 0xff; count *= 2)
{
result = queue->NewtonStep (recInvSqrt, count);
// Test that ns-3 value is exactly the same as the Linux value
NS_TEST_ASSERT_MSG_EQ (_codel_Newton_step (recInvSqrt, count), result,
"ns-3 NewtonStep() fails to match Linux equivalent");
}
}
}
/**
@@ -373,7 +367,7 @@ public:
* \param t
* \returns the codel control law
*/
uint32_t _codel_control_law (Ptr<CoDelQueueDisc> queue, uint32_t t);
uint32_t _codel_control_law (uint32_t t, uint32_t interval, uint32_t recInvSqrt);
};
CoDelQueueDiscControlLawTest::CoDelQueueDiscControlLawTest ()
@@ -384,9 +378,9 @@ CoDelQueueDiscControlLawTest::CoDelQueueDiscControlLawTest ()
// The following code borrowed from Linux codel.h,
// except the addition of queue parameter
uint32_t
CoDelQueueDiscControlLawTest::_codel_control_law (Ptr<CoDelQueueDisc> queue, uint32_t t)
CoDelQueueDiscControlLawTest::_codel_control_law (uint32_t t, uint32_t interval, uint32_t recInvSqrt)
{
return t + _reciprocal_scale (queue->Time2CoDel (queue->m_interval), queue->m_recInvSqrt << REC_INV_SQRT_SHIFT_ns3);
return t + _reciprocal_scale (interval, recInvSqrt << REC_INV_SQRT_SHIFT_ns3);
}
// End Linux borrrow
@@ -395,18 +389,19 @@ CoDelQueueDiscControlLawTest::DoRun (void)
{
Ptr<CoDelQueueDisc> queue = CreateObject<CoDelQueueDisc> ();
/* Spot check a few points of m_dropNext
The integer approximations in Linux should be within
2% of the true floating point value obtained in ns-3
*/
uint32_t dropNextTestVals [4] = {292299, 341128, 9804717, 55885007};
// Check a few points within the operational range of ControlLaw
uint32_t interval = queue->Time2CoDel (MilliSeconds (100));
for (int i = 0; i < 4; ++i)
uint32_t codelTimeVal;
for (Time timeVal = Seconds (0); timeVal <= Seconds (20); timeVal += MilliSeconds (100))
{
uint32_t ns3Result = queue->ControlLaw(dropNextTestVals[i]);
uint32_t linuxResult = _codel_control_law(queue, dropNextTestVals[i]);
NS_TEST_EXPECT_MSG_EQ((0.98 * ns3Result < linuxResult && linuxResult < 1.02 * ns3Result), true,
"Linux result should stay within 2% of ns-3 result");
for (uint16_t recInvSqrt = 0xff; recInvSqrt > 0; recInvSqrt /= 2)
{
codelTimeVal = queue->Time2CoDel (timeVal);
uint32_t ns3Result = queue->ControlLaw (codelTimeVal, interval, recInvSqrt);
uint32_t linuxResult = _codel_control_law (codelTimeVal, interval, recInvSqrt);
NS_TEST_EXPECT_MSG_EQ (ns3Result, linuxResult, "Linux result for ControlLaw should equal ns-3 result");
}
}
}