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Add an attention bias subclass for a lower right causal masking#114823

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Add an attention bias subclass for a lower right causal masking#114823
drisspg wants to merge 26 commits intogh/drisspg/12/basefrom
gh/drisspg/12/head

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@drisspg drisspg commented Nov 30, 2023

Summary

This PR introduces a new Tensor subclass that is designed to be used with torch.nn.functional.scaled_dot_product_attention. Currently we have a boolean is_causal flag that allows users to do do causal masking without the need to actually create the "realized" attention bias and pass into sdpa. We originally added this flag since there is native support in both fused kernels we support. This provides a big performance gain ( the kernels only need to iterate over ~0.5x the sequence, and for very large sequence lengths this can provide vary large memory improvements.

The flag was introduced when the early on in the kernel development and at the time it was implicitly meant to "upper_left" causal attention. This distinction only matters when the attention_bias is not square. For a more detailed break down see: #108108. The kernels default behavior has since changed, largely due to the rise of autogressive text generation. And unfortunately this would lead to a BC break. In the long term it may actually be beneficial to change the default meaning of is_causal to represent lower_right causal masking.

The larger theme though is laid here: #110681. The thesis being that there is alot of innovation in SDPA revolving around the attention_bias being used. This is the first in hopefully a few more attention_biases that we would like to add. The next interesting one would be sliding_window which is used by the popular mistral model family.

Stack from ghstack (oldest at bottom):

Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.

+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+

cc @albanD @mruberry @jbschlosser @walterddr @mikaylagawarecki

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🧪 See artifacts and rendered test results at hud.pytorch.org/pr/114823

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✅ You can merge normally! (1 Unrelated Failure)

As of commit 80b03db with merge base 597d3fb (image):

FLAKY - The following job failed but was likely due to flakiness present on trunk:

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Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.4320973389745877 |            |           |           |           |           |                |          |
|   Max   | 2.577393980674173  |    128     |    32     |    512    |   4097    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.942474845104863  |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
…sking"

# Summary
This PR introduces a new Tensor subclass that is designed to be used with torch.nn.functional.scaled_dot_product_attention. Currently we have a boolean `is_causal` flag that allows users to do do causal masking without the need to actually create the "realized" attention bias and pass into sdpa. We originally added this flag since there is native support in both fused kernels we support. This provides a big performance gain ( the kernels only need to iterate over ~0.5x the sequence, and for very large sequence lengths this can provide vary large memory improvements.

The flag was introduced when the early on in the kernel development and at the time it was implicitly meant to "upper_left" causal attention. This distinction only matters when the attention_bias is not square. For a more detailed break down see: #108108. The kernels default behavior has since changed, largely due to the rise of autogressive text generation. And unfortunately this would lead to a BC break. In the long term it may actually be beneficial to change the default meaning of `is_causal` to represent lower_right causal masking.

The larger theme though is laid here: #110681. The thesis being that there is alot of innovation in SDPA revolving around the attention_bias being used. This is the first in hopefully a few more attention_biases that we would like to add. The next interesting one would be `sliding_window` which is used by the popular mistral model family. 



Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
…sking"

# Summary
This PR introduces a new Tensor subclass that is designed to be used with torch.nn.functional.scaled_dot_product_attention. Currently we have a boolean `is_causal` flag that allows users to do do causal masking without the need to actually create the "realized" attention bias and pass into sdpa. We originally added this flag since there is native support in both fused kernels we support. This provides a big performance gain ( the kernels only need to iterate over ~0.5x the sequence, and for very large sequence lengths this can provide vary large memory improvements.

The flag was introduced when the early on in the kernel development and at the time it was implicitly meant to "upper_left" causal attention. This distinction only matters when the attention_bias is not square. For a more detailed break down see: #108108. The kernels default behavior has since changed, largely due to the rise of autogressive text generation. And unfortunately this would lead to a BC break. In the long term it may actually be beneficial to change the default meaning of `is_causal` to represent lower_right causal masking.

The larger theme though is laid here: #110681. The thesis being that there is alot of innovation in SDPA revolving around the attention_bias being used. This is the first in hopefully a few more attention_biases that we would like to add. The next interesting one would be `sliding_window` which is used by the popular mistral model family. 



Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
…sking"

# Summary
This PR introduces a new Tensor subclass that is designed to be used with torch.nn.functional.scaled_dot_product_attention. Currently we have a boolean `is_causal` flag that allows users to do do causal masking without the need to actually create the "realized" attention bias and pass into sdpa. We originally added this flag since there is native support in both fused kernels we support. This provides a big performance gain ( the kernels only need to iterate over ~0.5x the sequence, and for very large sequence lengths this can provide vary large memory improvements.

The flag was introduced when the early on in the kernel development and at the time it was implicitly meant to "upper_left" causal attention. This distinction only matters when the attention_bias is not square. For a more detailed break down see: #108108. The kernels default behavior has since changed, largely due to the rise of autogressive text generation. And unfortunately this would lead to a BC break. In the long term it may actually be beneficial to change the default meaning of `is_causal` to represent lower_right causal masking.

The larger theme though is laid here: #110681. The thesis being that there is alot of innovation in SDPA revolving around the attention_bias being used. This is the first in hopefully a few more attention_biases that we would like to add. The next interesting one would be `sliding_window` which is used by the popular mistral model family. 



Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
…sking"

# Summary
This PR introduces a new Tensor subclass that is designed to be used with torch.nn.functional.scaled_dot_product_attention. Currently we have a boolean `is_causal` flag that allows users to do do causal masking without the need to actually create the "realized" attention bias and pass into sdpa. We originally added this flag since there is native support in both fused kernels we support. This provides a big performance gain ( the kernels only need to iterate over ~0.5x the sequence, and for very large sequence lengths this can provide vary large memory improvements.

The flag was introduced when the early on in the kernel development and at the time it was implicitly meant to "upper_left" causal attention. This distinction only matters when the attention_bias is not square. For a more detailed break down see: #108108. The kernels default behavior has since changed, largely due to the rise of autogressive text generation. And unfortunately this would lead to a BC break. In the long term it may actually be beneficial to change the default meaning of `is_causal` to represent lower_right causal masking.

The larger theme though is laid here: #110681. The thesis being that there is alot of innovation in SDPA revolving around the attention_bias being used. This is the first in hopefully a few more attention_biases that we would like to add. The next interesting one would be `sliding_window` which is used by the popular mistral model family. 



Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

[ghstack-poisoned]
drisspg added a commit that referenced this pull request Dec 6, 2023
ghstack-source-id: cb25232
Pull Request resolved: #114823
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drisspg commented Dec 6, 2023

@pytorchbot merge

@pytorch-bot pytorch-bot bot added the ciflow/trunk Trigger trunk jobs on your pull request label Dec 6, 2023
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@drisspg drisspg added release notes: onnx torch.onnx related changes that should show up in the release notes release notes: python_frontend python frontend release notes category labels Dec 6, 2023
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drisspg commented Dec 6, 2023

@pytorchbot merge

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@facebook-github-bot facebook-github-bot deleted the gh/drisspg/12/head branch December 9, 2023 15:26
dmenig pushed a commit to dmenig/pytorch that referenced this pull request Dec 21, 2023
…rch#114823)

# Summary
This PR introduces a new Tensor subclass that is designed to be used with torch.nn.functional.scaled_dot_product_attention. Currently we have a boolean `is_causal` flag that allows users to do do causal masking without the need to actually create the "realized" attention bias and pass into sdpa. We originally added this flag since there is native support in both fused kernels we support. This provides a big performance gain ( the kernels only need to iterate over ~0.5x the sequence, and for very large sequence lengths this can provide vary large memory improvements.

The flag was introduced when the early on in the kernel development and at the time it was implicitly meant to "upper_left" causal attention. This distinction only matters when the attention_bias is not square. For a more detailed break down see: pytorch#108108. The kernels default behavior has since changed, largely due to the rise of autogressive text generation. And unfortunately this would lead to a BC break. In the long term it may actually be beneficial to change the default meaning of `is_causal` to represent lower_right causal masking.

The larger theme though is laid here: pytorch#110681. The thesis being that there is alot of innovation in SDPA revolving around the attention_bias being used. This is the first in hopefully a few more attention_biases that we would like to add. The next interesting one would be `sliding_window` which is used by the popular mistral model family.

Results from benchmarking, I improved the meff_attention perf hence the slightly decreased max perf.
```Shell
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
|  Type   |      Speedup       | batch_size | num_heads | q_seq_len | k_seq_len | embed_dim |     dtype      | head_dim |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
| Average | 1.2388050062214226 |            |           |           |           |           |                |          |
|   Max   | 1.831672915579016  |    128     |    32     |   1024    |   2048    |   2048    | torch.bfloat16 |    64    |
|   Min   | 0.9430534166730135 |     1      |    16     |    256    |    416    |   2048    | torch.bfloat16 |   128    |
+---------+--------------------+------------+-----------+-----------+-----------+-----------+----------------+----------+
```

Pull Request resolved: pytorch#114823
Approved by: https://github.com/cpuhrsch
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