©2016 GlobalLogic Inc.

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.NET Performance Boost

By Andrii Antilikatorov

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Optimize or not optimize?

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Quiz

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Jagged arrays vs 2D arrays

4571ns2864ns

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Jagged arrays

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FOR vs FOREACH

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FOR vs FOREACH

… it depends

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FOR vs FOREACH

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Performance of try...catch

2555ns 674ns

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Create new collection or clear existing one?

645ns

501ns

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String pool

Can be disabled with CompilationRelaxationsAttribute

By default interns only string literals

Works great in multithreaded code

Has the same lifetime as CLR

May cause troubles if interning went out of control

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Avoiding Boxing

bool areEqual = v1.Equals(v2);

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Avoiding Boxing

bool areEqual = v1.Equals(v2);

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Avoiding Boxing

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Avoiding Boxing

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Avoiding Boxing

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Avoiding Boxing

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Avoiding Boxing

Use value types if objects are small and supposed to be used often.

Value types are useful for memory compaction.

Override Equals(), “==“ (“!=“). Implement IEquatable interface.

Override GetHashCode().

Make value types immutable.

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Cost of method calls

CALL

CALLVIRTDependency Injection

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Parameter order performance

952ms

2224ms

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Field access optimization

15.86ns

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Field access optimization

5.18ns

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Multiple return values

1.64ns

0.32ns

5.40ns

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Tuple/KeyValuePair performance

Tuple KeyValuePair

Allocate 8.23ns 0.32ns

Pass as argument 1.93ns 2.57ns

Return 6.09ns 1.91ns

Load from List 2.79ns 4.18ns

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Array Copy

1343ns

1013ns

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Performance of DateTime

264ns

16 ns

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Memory Access

Off-Heap

(Unmanaged)

Memory-Mapped Files

Heap

(Managed)

1.068s1.096s

LOH optimization

P/Invoke, COM, Marshalling

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Memory-Mapped Files

Ideal to access file on disk without

performing I/O operations

The most efficient for cross-

process communication.

Allows properly protecting the

content and synchronize access.

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Memory Alignment

Type alignment Page size alignment

Cache line alignment

Memory Alignment

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Comparing Aligned/Unaligned Access Performance

Type aligned access provides better performance than

unaligned access.

Memory access that spans 2 cache lines has far worse

performance than aligned mid-cache line access.

Cache line access performance changes based on

cache line location.

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Type-aligned vs unaligned Access Test

Number of pages

Alignment

Relative cost

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Comparing Aligned/Unaligned Access Performance

Type aligned access provides better performance than

unaligned access.

Memory access that spans 2 cache lines has far worse

performance than aligned mid-cache line access.

Cache line access performance changes based on

cache line location.

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Cross-line cache access

Number of pages

Offset

Relative cost

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Comparing Aligned/Unaligned Access Performance

Type aligned access provides better performance than

unaligned access.

Memory access that spans 2 cache lines has far worse

performance than aligned mid-cache line access.

Cache line access performance changes based on

cache line location.

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Comparing Aligned/Unaligned Access Performance

Type aligned access provides better performance than

unaligned access.

Memory access that spans 2 cache lines has far worse

performance than aligned mid-cache line access.

Cache line access performance changes based on

cache line location.

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Cost of Access Based on Cache Line LocationOffset

Number of pagesRelative cost

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Comparing Aligned/Unaligned Access Performance

Type aligned access provides better performance than

unaligned access.

Memory access that spans 2 cache lines has far worse

performance than aligned mid-cache line access.

Cache line access performance changes based on

cache line location.

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Synchronized or volatile?

Volatile variables are less expensive than synchronized blocks

Volatile are thread-safe for atomic operations

Volatile acquires lock on variable, therefore not thread- safe

for non-atomic operations

Synchronized blocks have no performance impact if no

synchronization required

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Synchronized or volatile?

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Synchronized or volatile?

MESI Protocol

• Modified

• Exclusive

• Shared

• Invalid

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Synchronized or volatile?

Volatile variables are less expensive than synchronized blocks

Volatile are thread-safe for atomic operations

Volatile acquires lock on variable, therefore not thread- safe

for non-atomic operations

Synchronized blocks have no performance impact if no

synchronization required

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Summary

Architecture first

Remember rule 80/20

Don’t try to write ideal code from the beginning

Don’t create bicycles

Don’t optimize for particular platform

©2016 GlobalLogic Inc.