OV - exec - Function sortAtomsById

	Function: sortAtomsById	Module: exec	Source: haloExchange.c:653-661	Coverage (incl. loops): 0.11% \| (excl. loops): 0.11%

/home/eoseret/qaas/qaas_runs/178-176-0594/intel/CoMD/build/CoMD/CoMD/src-openmp/haloExchange.c: 653 - 661

--------------------------------------------------------------------------------

653: {

654:    int aId = ((AtomMsg*) a)->gid;

655:    int bId = ((AtomMsg*) b)->gid;

656:    assert(aId != bId);

657:

658:    if (aId < bId)

659:       return -1;

660:    return 1;

661: }

0x414100 LDR	W2, [X0]

0x414104 LDR	W0, [X1]

0x414108 CMP	W2, W0

0x41410c B.EQ	41411c

0x414110 MOVN	W6, #0

0x414114 CSINC	W0, W6, WZR, #11

0x414118 RET

0x41411c ADRP	X3,

0x414120 ADRP	X1,

0x414124 STP	X29, X30, [SP, #1008]!

0x414128 ADD	X4, X3, #3288

0x41412c ADRP	X5,

0x414130 ADD	X29, SP, #0

0x414134 ADD	X3, X4, #24

0x414138 ADD	X1, X1, #2592

0x41413c ADD	X0, X5, #2760

0x414140 MOVZ	W2, #656

0x414144 BL	4101c0

Coverage (%)	Name	Source Location	Module
►4.27+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►3.66+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►3.66+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►3.05+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►3.05+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►2.44+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►2.44+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►2.44+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.83+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.83+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.83+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.83+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.83+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.83+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6
►1.22+	msort_with_tmp.part.0		libc.so.6
○	indirect_msort_with_tmp		libc.so.6
○	__GI___qsort_r		libc.so.6
○	sortAtomsInCell	haloExchange.c:633	exec
○	redistributeAtoms._omp_fn.0	timestep.c:154	exec
○	omp_fulfill_event		libgomp.so.1.0.0
○	start_thread		libc.so.6
○	thread_start		libc.so.6

min	med	avg	max

Percentile Index	10	20	30	40	50	60	70	80	90	100
Value

min	med	avg	max

Percentile Index	10	20	30	40	50	60	70	80	90	100
Value

Path /

Average path: Display a virtual path defined by average values of all real paths

The code analyzed by CQA in that panel excludes loops and represents 0.11% of application time for run gcc_4

Source file and lines	haloExchange.c:653-661
Module	exec

The function is defined in /home/eoseret/qaas/qaas_runs/178-176-0594/intel/CoMD/build/CoMD/CoMD/src-openmp/haloExchange.c:653-661.

The structure of this function is probably <if then [else] end>.

The presence of multiple execution paths is typically the main/first bottleneck.
Try to simplify control inside function: ideally, try to remove all conditional expressions, for example by (if applicable):

hoisting them (moving them outside the function)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Vectorization

Your function is not vectorized. Only 17% of vector register length is used (average across all VPU instructions). By vectorizing your function, you can lower the cost of an iteration from 2.00 to 0.36 cycles (5.57x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized function can use their full power.

Workaround

Try another compiler or update/tune your current one
Make array accesses unit-stride:
- If your function streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

No data for this section

Matching between your function (in the source code) and the binary function

The binary function does not contain any FP arithmetical operations. The binary function is loading 6 bytes.

General properties

nb instructions	11
nb uops	11
loop length	44
used w registers	3
used x registers	4.50
used b registers	0
used h registers	0
used s registers	0.50
used d registers	0
used q registers	0
used v registers	0
used z registers	0
nb stack references	0.50

Front-end

MACRO FUSION NOT POSSIBLE

micro-operation queue	1.38 cycles
front end	1.38 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	1.00	1.00	1.88	1.88	1.88	1.88	0.00	0.00	0.00	0.00	0.92	0.75	0.83	0.25	0.25
cycles	1.00	1.00	1.88	1.88	1.88	1.88	0.00	0.00	0.00	0.00	0.92	0.75	0.83	0.25	0.25

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions

Cycles summary

Front-end	1.38
Dispatch	2.00
Overall L1	2.00

Vectorization ratios

all	0%
load	0%
store	0%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Vector efficiency ratios

all	17%
load	12%
store	50%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	25%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	12%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each call to the function takes 2.00 cycles. At this rate:

4% of peak load performance is reached (4.00 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

The code analyzed by CQA in that panel excludes loops and represents 0.11% of application time for run gcc_4

Source file and lines	haloExchange.c:653-661
Module	exec

hoisting them (moving them outside the function)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Vectorization

Your function is not vectorized. 8 data elements could be processed at once in vector registers. By vectorizing your function, you can lower the cost of an iteration from 1.00 to 0.12 cycles (8.00x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized function can use their full power.

Workaround

Try another compiler or update/tune your current one
Make array accesses unit-stride:
- If your function streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

No data for this section

Matching between your function (in the source code) and the binary function

The binary function does not contain any FP arithmetical operations. The binary function is loading 6 bytes.

General properties

nb instructions	7
nb uops	7
loop length	28
used w registers	4
used x registers	2
used b registers	0
used h registers	0
used s registers	0
used d registers	0
used q registers	0
used v registers	0
used z registers	0
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	0.88 cycles
front end	0.88 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	1.00	1.00	0.75	0.75	0.75	0.75	0.00	0.00	0.00	0.00	0.67	0.67	0.67	0.00	0.00
cycles	1.00	1.00	0.75	0.75	0.75	0.75	0.00	0.00	0.00	0.00	0.67	0.67	0.67	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions

Cycles summary

Front-end	0.88
Dispatch	1.00
Overall L1	1.00

Vectorization ratios

all	0%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Vector efficiency ratios

all	12%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	12%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each call to the function takes 1.00 cycles. At this rate:

6% of peak load performance is reached (6.00 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Found no such bottlenecks.

ASM code

In the binary file, the address of the function is: 414100

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P10	P11	P12	Latency	Recip. throughput	Vectorization
LDR W2, [X0]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	N/A
LDR W0, [X1]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	N/A
CMP W2, W0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.33	N/A
B.EQ 41411c <sortAtomsById+0x1c>	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A
MOVN W6, #0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (12.5%)
CSINC W0, W6, WZR, #11	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	N/A
RET	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A

The code analyzed by CQA in that panel excludes loops and represents 0.11% of application time for run gcc_4

Source file and lines	haloExchange.c:653-661
Module	exec

hoisting them (moving them outside the function)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Vectorization

Your function is not vectorized. Only 23% of vector register length is used (average across all VPU instructions). By vectorizing your function, you can lower the cost of an iteration from 3.00 to 0.59 cycles (5.05x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized function can use their full power.

Workaround

Try another compiler or update/tune your current one
Make array accesses unit-stride:
- If your function streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

No data for this section

CALL instructions

Detected function call instructions.

Details

Calling (and then returning from) a function prevents many compiler optimizations (like vectorization), breaks control flow (which reduces pipeline performance) and executes extra instructions to save/restore the registers used inside it, which is very expensive (dozens of cycles). Consider to inline small functions.

unknown: 1 occurrences►
- /home/eoseret/qaas/qaas_runs/178-176-0594/intel/CoMD/build/CoMD/CoMD/src-openmp/haloExchange.c:656

Matching between your function (in the source code) and the binary function

The binary function does not contain any FP arithmetical operations. The binary function is loading 6 bytes.

General properties

nb instructions	15
nb uops	15
loop length	60
used w registers	2
used x registers	7
used b registers	0
used h registers	0
used s registers	1
used d registers	0
used q registers	0
used v registers	0
used z registers	0
nb stack references	1

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	1.88 cycles
front end	1.88 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	1.00	1.00	3.00	3.00	3.00	3.00	0.00	0.00	0.00	0.00	1.17	0.83	1.00	0.50	0.50
cycles	1.00	1.00	3.00	3.00	3.00	3.00	0.00	0.00	0.00	0.00	1.17	0.83	1.00	0.50	0.50

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions

Cycles summary

Front-end	1.88
Dispatch	3.00
Overall L1	3.00

Vectorization ratios

all	0%
load	0%
store	0%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Vector efficiency ratios

all	23%
load	12%
store	50%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	25%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	12%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each call to the function takes 3.00 cycles. At this rate:

2% of peak load performance is reached (2.00 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Found no such bottlenecks.

ASM code

In the binary file, the address of the function is: 414100

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P10	P11	P12	P13	P14	Latency	Recip. throughput	Vectorization
LDR W2, [X0]	1	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (12.5%)
LDR W0, [X1]	1	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
CMP W2, W0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.33	scal (12.5%)
B.EQ 41411c <sortAtomsById+0x1c>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	1	0.50	N/A
ADRP X3, <42111c>	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	scal (25.0%)
ADRP X1, <420120>	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	N/A
STP X29, X30, [SP, #1008]!	1	0	0	0.25	0.25	0.25	0.25	0.50	0.50	0	0.50	0.50	1	0.50	scal (50.0%)
ADD X4, X3, #3288	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	scal (25.0%)
ADRP X5, <42012c>	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	N/A
ADD X29, SP, #0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X3, X4, #24	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X1, X1, #2592	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	N/A
ADD X0, X5, #2760	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	N/A
MOVZ W2, #656	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	1	0.25	scal (12.5%)
BL 4101c0 <@plt_start@+0x1a0>	1	0.50	0.50	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A

Name	Coverage (%)	Time (s)
○sortAtomsById	0.11	0.02

Report Configuration

Vectorization

Details

Workaround

Matching between your function (in the source code) and the binary function

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Vectorization

Details

Workaround

Matching between your function (in the source code) and the binary function

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code

Vectorization

Details

Workaround

CALL instructions

Details

Matching between your function (in the source code) and the binary function

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code