• WANG Rui's avatar
    LoongArch: Optimize memory ops (memset/memcpy/memmove) · 8941e93c
    WANG Rui authored
    To optimize memset()/memcpy()/memmove() and so on, we use a jump table
    to dispatch cases for short data lengths; and for long data lengths, we
    split the destination into head part (first 8 bytes), tail part (last 8
    bytes) and middle part. The head part and tail part may be at unaligned
    addresses, while the middle part is always aligned (the middle part is
    allowed to overlap the head/tail part). In this way, the first and last
    8 bytes may be unaligned accesses, but we can make sure the data in the
    middle is processed at an aligned destination address.
    
    We have tested micro-bench[1] on a Loongson-3C5000 16-core machine (2.2GHz):
    
    1. memset
    
    | length | src offset | dst offset | speed before | speed after | %       |
    |--------|------------|------------|--------------|-------------|---------|
    | 8      | 0          | 0          | 696.191      | 1518.785    | 118.16% |
    | 8      | 0          | 1          | 696.325      | 1518.937    | 118.14% |
    | 50     | 0          | 0          | 969.976      | 8053.902    | 730.32% |
    | 50     | 0          | 1          | 970.034      | 8058.475    | 730.74% |
    | 300    | 0          | 0          | 5876.612     | 16544.703   | 181.53% |
    | 300    | 0          | 1          | 5030.849     | 16549.011   | 228.95% |
    | 1200   | 0          | 0          | 11797.077    | 16752.137   | 42.00%  |
    | 1200   | 0          | 1          | 5687.141     | 16645.233   | 192.68% |
    | 4000   | 0          | 0          | 15723.27     | 16761.557   | 6.60%   |
    | 4000   | 0          | 1          | 5906.114     | 16732.316   | 183.30% |
    | 8000   | 0          | 0          | 16751.403    | 16770.002   | 0.11%   |
    | 8000   | 0          | 1          | 5995.449     | 16754.07    | 179.45% |
    
    2. memcpy
    
    | length | src offset | dst offset | speed before | speed after | %       |
    |--------|------------|------------|--------------|-------------|---------|
    | 8      | 0          | 0          | 696.2        | 1670.605    | 139.96% |
    | 8      | 0          | 1          | 696.325      | 1671.138    | 139.99% |
    | 50     | 0          | 0          | 969.974      | 8724.999    | 799.51% |
    | 50     | 0          | 1          | 970.032      | 8730.138    | 799.98% |
    | 300    | 0          | 0          | 5564.662     | 16272.652   | 192.43% |
    | 300    | 0          | 1          | 4670.436     | 14972.842   | 220.59% |
    | 1200   | 0          | 0          | 10740.23     | 16751.728   | 55.97%  |
    | 1200   | 0          | 1          | 5027.741     | 14874.564   | 195.85% |
    | 4000   | 0          | 0          | 15122.367    | 16737.642   | 10.68%  |
    | 4000   | 0          | 1          | 5536.918     | 14890.397   | 168.93% |
    | 8000   | 0          | 0          | 16505.453    | 16553.543   | 0.29%   |
    | 8000   | 0          | 1          | 5821.619     | 14841.804   | 154.94% |
    
    3. memmove
    
    | length | src offset | dst offset | speed before | speed after | %       |
    |--------|------------|------------|--------------|-------------|---------|
    | 8      | 0          | 0          | 982.693      | 1670.568    | 70.00%  |
    | 8      | 0          | 1          | 983.023      | 1671.174    | 70.00%  |
    | 50     | 0          | 0          | 1230.87      | 8727.625    | 609.06% |
    | 50     | 0          | 1          | 1232.515     | 8730.138    | 608.32% |
    | 300    | 0          | 0          | 6490.375     | 16296.993   | 151.09% |
    | 300    | 0          | 1          | 4282.687     | 14972.842   | 249.61% |
    | 1200   | 0          | 0          | 11742.755    | 16752.546   | 42.66%  |
    | 1200   | 0          | 1          | 5039.338     | 14872.951   | 195.14% |
    | 4000   | 0          | 0          | 15467.786    | 16737.09    | 8.21%   |
    | 4000   | 0          | 1          | 5009.905     | 14890.542   | 197.22% |
    | 8000   | 0          | 0          | 16489.664    | 16553.273   | 0.39%   |
    | 8000   | 0          | 1          | 5823.786     | 14858.646   | 155.14% |
    
    * speed: MB/s
    * length: byte
    
    [1] https://github.com/heiher/mem-benchSigned-off-by: default avatarWANG Rui <wangrui@loongson.cn>
    Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
    8941e93c
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