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multithreading_assembly_perf_test - 2025-05-19 15:45:40 - MAQAO 2.21.2

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Stylizer  

[ 4 / 4 ] Application profile is long enough (64.99 s)

To have good quality measurements, it is advised that the application profiling time is greater than 10 seconds.

[ 3 / 3 ] Optimization level option is correctly used

[ 2.95 / 3 ] Most of time spent in analyzed modules comes from functions compiled with -g and -fno-omit-frame-pointer

-g option gives access to debugging informations, such are source locations. -fno-omit-frame-pointer improve the accuracy of callchains found during the application profiling.

[ 2 / 3 ] Security settings from the host restrict profiling. Some metrics will be missing or incomplete.

Current value for kernel.perf_event_paranoid is 2. If possible, set it to 1 or check with your system administrator which flag can be used to achieve this.

[ 2.95 / 3 ] Architecture specific option -march=znver4 is used

[ 0 / 2 ] Too much execution time spent in category "Others" (25.99 %)

If the category "Others" represents more than 20% of the execution time, it means that the application profile misses a representative part of the application. Examine functions details to properly identify “Others” category components. Rerun after adding most represented library names (e.g. more than 20% of coverage) to external_libraries (the names can be directly provided by ONE View)

[ 1 / 1 ] Lstopo present. The Topology lstopo report will be generated.

[ 0 / 0 ] Fastmath not used

Consider to add ffast-math to compilation flags (or replace -O3 with -Ofast) to unlock potential extra speedup by relaxing floating-point computation consistency. Warning: floating-point accuracy may be reduced and the compliance to IEEE/ISO rules/specifications for math functions will be relaxed, typically 'errno' will no longer be set after calling some math functions.

Strategizer  

[ 0 / 4 ] Too little time of the experiment time spent in analyzed loops (0.35%)

If the time spent in analyzed loops is less than 30%, standard loop optimizations will have a limited impact on application performances.

[ 0 / 4 ] CPU activity is below 90% (23.23%)

CPU cores are idle more than 10% of time. Threads supposed to run on these cores are probably IO/sync waiting. Some hints: use faster filesystems to read/write data, improve parallel load balancing and/or scheduling.

[ 0 / 4 ] A significant amount of threads are idle (86.22%)

On average, more than 10% of observed threads are idle. Such threads are probably IO/sync waiting. Some hints: use faster filesystems to read/write data, improve parallel load balancing and/or scheduling.

[ 3 / 4 ] Affinity stability is lower than 90% (88.40%)

Threads are often migrating to other CPU cores/threads. For OpenMP, typically set (OMP_PLACES=cores OMP_PROC_BIND=close) or (OMP_PLACES=threads OMP_PROC_BIND=spread). With OpenMPI + OpenMP, use --bind-to core --map-by node:PE=$OMP_NUM_THREADS --report-bindings. With IntelMPI + OpenMP, set I_MPI_PIN_DOMAIN=omp:compact or I_MPI_PIN_DOMAIN=omp:scatter and use -print-rank-map.

[ 0 / 4 ] Loop profile is flat

No hotspot found in the application (greatest loop coverage is 0.20%), and the twenty hottest loops cumulated coverage is lower than 20% of the application profiled time (0.35%)

[ 0 / 4 ] Too little time of the experiment time spent in analyzed innermost loops (0.14%)

If the time spent in analyzed innermost loops is less than 15%, standard innermost loop optimizations such as vectorisation will have a limited impact on application performances.

[ 0 / 3 ] Cumulative Outermost/In between loops coverage (0.21%) greater than cumulative innermost loop coverage (0.14%)

Having cumulative Outermost/In between loops coverage greater than cumulative innermost loop coverage will make loop optimization more complex

[ 3 / 3 ] Less than 10% (0.00%) is spend in BLAS1 operations

It could be more efficient to inline by hand BLAS1 operations

[ 2 / 2 ] Less than 10% (0.07%) is spend in BLAS2 operations

BLAS2 calls usually could make a poor cache usage and could benefit from inlining.

[ 2 / 2 ] Less than 10% (0.00%) is spend in Libm/SVML (special functions)

Optimizer

Loop IDAnalysisPenalty Score
Loop 314 - multithreading_assembly_perf_test+Execution Time: 0 % - Vectorization Ratio: 13.01 % - Vector Length Use: 14.29 %
Loop Computation Issues+2
[SA] Presence of a large number of scalar integer instructions - Simplify loop structure, perform loop splitting or perform unroll and jam. This issue costs 2 points.2
Control Flow Issues+4
[SA] Presence of calls - Inline either by compiler or by hand and use SVML for libm calls. There are 2 issues (= calls) costing 1 point each.2
[SA] Non innermost loop (InBetween) - Collapse loop with innermost ones. This issue costs 2 points.2
Data Access Issues+7
[SA] Inefficient vectorization: more than 10% of the vector loads instructions are unaligned - When allocating arrays, don’t forget to align them. There are 0 issues ( = arrays) costing 2 points each0
[SA] Presence of special instructions executing on a single port (INSERT/EXTRACT) - Simplify data access and try to get stride 1 access. There are 5 issues (= instructions) costing 1 point each.5
[SA] More than 20% of the loads are accessing the stack - Perform loop splitting to decrease pressure on registers. This issue costs 2 points.2
Vectorization Roadblocks+1004
[SA] Presence of calls - Inline either by compiler or by hand and use SVML for libm calls. There are 2 issues (= calls) costing 1 point each.2
[SA] Too many paths (at least 1000 paths) - Simplify control structure. There are at least 1000 issues ( = paths) costing 1 point.1000
[SA] Non innermost loop (InBetween) - Collapse loop with innermost ones. This issue costs 2 points.2
Inefficient Vectorization+5
[SA] Presence of special instructions executing on a single port (INSERT/EXTRACT) - Simplify data access and try to get stride 1 access. There are 5 issues (= instructions) costing 1 point each.5
Loop 375 - multithreading_assembly_perf_testExecution Time: 0 % - Vectorization Ratio: 100.00 % - Vector Length Use: 100.00 %
Loop 189 - multithreading_assembly_perf_test+Execution Time: 0 % - Vectorization Ratio: 0.00 % - Vector Length Use: 11.25 %
Control Flow Issues+2
[SA] Presence of calls - Inline either by compiler or by hand and use SVML for libm calls. There are 2 issues (= calls) costing 1 point each.2
Vectorization Roadblocks+2
[SA] Presence of calls - Inline either by compiler or by hand and use SVML for libm calls. There are 2 issues (= calls) costing 1 point each.2
Loop 445 - multithreading_assembly_perf_test+Execution Time: 0 % - Vectorization Ratio: 0.00 % - Vector Length Use: 7.81 %
Control Flow Issues+2
[SA] Several paths (2 paths) - Simplify control structure or force the compiler to use masked instructions. There are 2 issues ( = paths) costing 1 point each.2
Data Access Issues+4
[SA] Presence of indirect accesses - Use array restructuring or gather instructions to lower the cost. There are 1 issues ( = indirect data accesses) costing 4 point each.4
Vectorization Roadblocks+6
[SA] Several paths (2 paths) - Simplify control structure or force the compiler to use masked instructions. There are 2 issues ( = paths) costing 1 point each.2
[SA] Presence of indirect accesses - Use array restructuring or gather instructions to lower the cost. There are 1 issues ( = indirect data accesses) costing 4 point each.4
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