crc: crc32_iscsi_by8_02 opt when data become 16 bytes or less #375
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- Use CRC32 instruction to calculate:
a. short data no more than 16 bytes;
b. long data when folding until 16 bytes.
- Add fastpath for short data to make the procedure more efficient.
Signed-off-by: Maodi Ma <[email protected]>
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Thanks for the PR. This is now merged. |
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When data become 16 bytes or less, the final result is gained by folding and barrett reduction with
VPCLMULQDQincrc32_iscsi_by8_02. This is less efficient than usingCRC32instruction directly on x86 platform.In this commit, we use
CRC32instruction to calculate:_barrettand other deprecated codes are removed.Besides, we add several fastpaths for short data at the very beginning. It will notice the short data as early as possible and prevent it from the long control flow in the procedure. The entry points (i.e. 4/8/16 bytes) are choosed based on the balance of performance of all data length less than 16 bytes.
Performance data are listed below (iterations per second):