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APC

Some useful tuning

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2 caching mechanism

Memory cache

for long operations and calculations

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Opcode cache

for skipping code interpretation

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Opcode

The Vulcan Logic Disassembler

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Tuning opcode cache

apc.max_file_size (1M)

Files bigger then that wouldn't be cached.

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apc.num_files_hint (1000)

Number of files that will be cached. Increase it.

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apc.file_md5 (0)

Keep it 0, it's a lie

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apc.ttl (0)

How long the file will stay cached

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Tuning opcode cache

apc.stat (1)

Rechecking if file was updated. Set it to 0.

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Tuning opcode cache

strace -e trace=file httpd -X

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Tuning opcode cache

apc.stat (1)

Rechecking if file was updated. Set it to 0.

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apc.slam_defense (1)

Prevents mass caching on startup. Set to 0

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apc.write_lock (1)

Prevents locking of parallel requests

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apc.file_update_protection (2)

Seconds to wait before new file gets cached

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Extra control on opcode caching

apc.filter (null)

Regexp: cache only matching it files.

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apc.cache_by_default (1)

Caches all php files. If set to 0 - it would use the filter

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apc.canonicalize (1)

Convert relative path's into canonical.

Set to 0 and always use absolute path's.

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Now User Cache

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Concurrent locking

File locks

Basic locking mechanism. Very slow.

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IPC Semaphore locks

Semaphores (provided by the OS). Better then file locks

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Linux Futex locks

Linux specific mechanism. Significant gain. ( user space )

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Pthread mutexes

Almost same as futex ( kernel space)

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Spin locks

Extremely fast. Ported from Postgres. Eats your cpu

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Use igbinary

Serialization sucks

Example array: [1,2,'hi']

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Use igbinary

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Apc constants

Regular defines are uber slow

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Prime cache before start

Preload cache with data before going public

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apc_store()

apc_compile_file()