Design proposal for new ring buffer API #3848
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mikeagun
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mikeagun
changed the title
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Converting to draft while I make a few design updates. |
| * @returns Pointer to ring buffer manager. | ||
| */ | ||
| struct ring_buffer * | ||
| ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx, |
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How do we differentiate between callback vs poll?
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Updated the design so callback consumers now use the libbpf ring buffer manager, and direct mapped memory consumers use the new functions.
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I don't follow. How does Linux differentiate? Why would we want a different answer?
Splits the design so callback consumers use the existing libbpf APIs, and mapped memory consumers use the new windows-specific functions.
docs/RingBuffer.md
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| // Update consumer offset (and pad record length to multiple of 8). | ||
| consumer_offset += sizeof(rb_header_t) + (record->length + 7 & ~7); | ||
| WriteRelease64(cons_offset, consumer_offset); |
| 1. Call `ebpf_ring_buffer_get_buffer` to get pointers to the mapped producer/consumer pages. | ||
| 2. Call `ebpf_ring_buffer_get_wait_handle` to get the wait handle. | ||
| 3. Directly read records from the producer pages (and update consumer offset as we read). | ||
| 4. Call `WaitForSingleObject`/`WaitForMultipleObject` as needed to wait for new data to be available. |
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Line 6 says Linux supports polling consumers. What APIs do callers use on Linux to get this behavior?
Why can't those APIs work on Windows? Why are new ebpf_ APIs needed?
This document doesn't appear to answer any of these questions.
| * @returns Pointer to ring buffer manager. | ||
| */ | ||
| struct ring_buffer * | ||
| ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx, |
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I don't follow. How does Linux differentiate? Why would we want a different answer?
docs/RingBuffer.md
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| const struct ring_buffer_opts *opts); | ||
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| /** | ||
| * @brief poll ringbuf for new data (NOT CURRENTLY SUPPORTED) |
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Why not currently supported?
Description
Add docs/RingBuffer.md with proposal for new ebpf ring buffer map API exposing mapped memory so consumers can directly read the records written by the producer (similar to linux mmap/epoll style ring buffer consumer).
Testing
N/A
Documentation
Documentation only.
Installation
N/A