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Optimise Flow.copy with Buf_read.as_flow #663
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Excited to see this! ✨ If I find any other sore spots I'll try and be a little more proactive opening issues or tagging y'all 🙏🏼 it's been a busy week over here. And please feel more than welcome to bench against Riot, it may help me find bottlenecks like this too! Happy new year team, keep kicking ass 👏🏼 |
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I haven't fully explored this area of the code yet but this looks good to me!
By default, Flow.copy creates a 4KB buffer and copies the data through that. However, if the source of the copy is a buffered reader then it is much more efficient to use its buffer directly. This updates the flow you get from `Buf_read.as_flow` to offer this optimisation, and also updates the eio_posix backend's flow to use this optimisation when available (eio_linux already supported this). Detected in a benchmark by Leandro Ostera.
CHANGES: New features / API changes: - Add `Eio.Executor_pool` (@SGrondin ocaml-multicore/eio#639, reviewed by @talex5). Provides an easy way to distribute jobs across domains. - Add `Fiber.first ~combine` and `Fiber.n_any` (@SGrondin @talex5 ocaml-multicore/eio#587). Allows keeping both results in the case where multiple fibers succeed. - Add `Eio_mock.Backend.run_full` with auto-advancing mock clock (@talex5 ocaml-multicore/eio#644, reviewed by @SGrondin). Simplifies testing of code using clocks. - Add `Buf_write.printf` (@SGrondin @talex5 ocaml-multicore/eio#655). - Add `Net.listening_addr` (@mefyl ocaml-multicore/eio#555, reviewed by @patricoferris @talex5). Useful to get the socket's address if the OS assigns it. - Add `Promise.try_resolve` (@talex5 ocaml-multicore/eio#646). - Remove `Cancel_hook_failed` exception (@talex5 ocaml-multicore/eio#640). Didn't seem to be used and broke dscheck. Tracing: - Improve tracing (@TheLortex @patricoferris @talex5 ocaml-multicore/eio#656). Trace cancellation contexts and OS operations, and simplify API. - Add labels to switches (@talex5 ocaml-multicore/eio#661, reviewed by @SGrondin). - `Fiber.all`: use the parent fiber (@talex5 ocaml-multicore/eio#665, reviewed by @SGrondin). Cleans up the traces a bit. Performance: - Faster and simpler `Lf_queue` (@talex5 ocaml-multicore/eio#647, based on work by @polytypic). - Optimise `Flow.copy` with `Buf_read.as_flow` (@talex5 ocaml-multicore/eio#663, reviewed by @SGrondin, reported by @leostera). Bug fixes: - Fix handling of very long IO vectors (@talex5 ocaml-multicore/eio#653, reported by @Cjen1). - eio_posix: use `caml_enter_blocking_section` in more places (@talex5 ocaml-multicore/eio#654, reviewed by @SGrondin). - eio_posix: work around `caml_unix_alloc_sockaddr` bug (@talex5 ocaml-multicore/eio#651). - Remove default backtrace from `Switch.fail` (@talex5 ocaml-multicore/eio#664). Documentation: - Organise eio.mli better (@talex5 ocaml-multicore/eio#667). - Fix quoting of quotes in process error messages (@talex5 ocaml-multicore/eio#666, reviewed by @SGrondin). - Mention Path module in File and Fs documentation (@talex5 ocaml-multicore/eio#659, requested by @clecat). - Minor documentation updates (@SGrondin @talex5 ocaml-multicore/eio#670). Build / internals: - Allow closing synchronous streams (@talex5 ocaml-multicore/eio#641, reviewed by @SGrondin). This isn't currently exposed in the public interface. - Fix non-idempotent tests (@SGrondin ocaml-multicore/eio#662). - eio_windows: add explicit fmt dependency (@talex5 ocaml-multicore/eio#643).
CHANGES: New features / API changes: - Add `Eio.Executor_pool` (@SGrondin ocaml-multicore/eio#639, reviewed by @talex5). Provides an easy way to distribute jobs across domains. - Add `Fiber.first ~combine` and `Fiber.n_any` (@SGrondin @talex5 ocaml-multicore/eio#587). Allows keeping both results in the case where multiple fibers succeed. - Add `Eio_mock.Backend.run_full` with auto-advancing mock clock (@talex5 ocaml-multicore/eio#644, reviewed by @SGrondin). Simplifies testing of code using clocks. - Add `Buf_write.printf` (@SGrondin @talex5 ocaml-multicore/eio#655). - Add `Net.listening_addr` (@mefyl ocaml-multicore/eio#555, reviewed by @patricoferris @talex5). Useful to get the socket's address if the OS assigns it. - Add `Promise.try_resolve` (@talex5 ocaml-multicore/eio#646). - Remove `Cancel_hook_failed` exception (@talex5 ocaml-multicore/eio#640). Didn't seem to be used and broke dscheck. Tracing: - Improve tracing (@TheLortex @patricoferris @talex5 ocaml-multicore/eio#656). Trace cancellation contexts and OS operations, and simplify API. - Add labels to switches (@talex5 ocaml-multicore/eio#661, reviewed by @SGrondin). - `Fiber.all`: use the parent fiber (@talex5 ocaml-multicore/eio#665, reviewed by @SGrondin). Cleans up the traces a bit. Performance: - Faster and simpler `Lf_queue` (@talex5 ocaml-multicore/eio#647, based on work by @polytypic). - Optimise `Flow.copy` with `Buf_read.as_flow` (@talex5 ocaml-multicore/eio#663, reviewed by @SGrondin, reported by @leostera). Bug fixes: - Fix handling of very long IO vectors (@talex5 ocaml-multicore/eio#653, reported by @Cjen1). - eio_posix: use `caml_enter_blocking_section` in more places (@talex5 ocaml-multicore/eio#654, reviewed by @SGrondin). - eio_posix: work around `caml_unix_alloc_sockaddr` bug (@talex5 ocaml-multicore/eio#651). - Remove default backtrace from `Switch.fail` (@talex5 ocaml-multicore/eio#664). Documentation: - Organise eio.mli better (@talex5 ocaml-multicore/eio#667). - Fix quoting of quotes in process error messages (@talex5 ocaml-multicore/eio#666, reviewed by @SGrondin). - Mention Path module in File and Fs documentation (@talex5 ocaml-multicore/eio#659, requested by @clecat). - Minor documentation updates (@SGrondin @talex5 ocaml-multicore/eio#670). Build / internals: - Allow closing synchronous streams (@talex5 ocaml-multicore/eio#641, reviewed by @SGrondin). This isn't currently exposed in the public interface. - Fix non-idempotent tests (@SGrondin ocaml-multicore/eio#662). - eio_windows: add explicit fmt dependency (@talex5 ocaml-multicore/eio#643).
CHANGES: New features / API changes: - Add `Eio.Executor_pool` (@SGrondin ocaml-multicore/eio#639, reviewed by @talex5). Provides an easy way to distribute jobs across domains. - Add `Fiber.first ~combine` and `Fiber.n_any` (@SGrondin @talex5 ocaml-multicore/eio#587). Allows keeping both results in the case where multiple fibers succeed. - Add `Eio_mock.Backend.run_full` with auto-advancing mock clock (@talex5 ocaml-multicore/eio#644, reviewed by @SGrondin). Simplifies testing of code using clocks. - Add `Buf_write.printf` (@SGrondin @talex5 ocaml-multicore/eio#655). - Add `Net.listening_addr` (@mefyl ocaml-multicore/eio#555, reviewed by @patricoferris @talex5). Useful to get the socket's address if the OS assigns it. - Add `Promise.try_resolve` (@talex5 ocaml-multicore/eio#646). - Remove `Cancel_hook_failed` exception (@talex5 ocaml-multicore/eio#640). Didn't seem to be used and broke dscheck. Tracing: - Improve tracing (@TheLortex @patricoferris @talex5 ocaml-multicore/eio#656). Trace cancellation contexts and OS operations, and simplify API. - Add labels to switches (@talex5 ocaml-multicore/eio#661, reviewed by @SGrondin). - `Fiber.all`: use the parent fiber (@talex5 ocaml-multicore/eio#665, reviewed by @SGrondin). Cleans up the traces a bit. Performance: - Faster and simpler `Lf_queue` (@talex5 ocaml-multicore/eio#647, based on work by @polytypic). - Optimise `Flow.copy` with `Buf_read.as_flow` (@talex5 ocaml-multicore/eio#663, reviewed by @SGrondin, reported by @leostera). Bug fixes: - Fix handling of very long IO vectors (@talex5 ocaml-multicore/eio#653, reported by @Cjen1). - eio_posix: use `caml_enter_blocking_section` in more places (@talex5 ocaml-multicore/eio#654, reviewed by @SGrondin). - eio_posix: work around `caml_unix_alloc_sockaddr` bug (@talex5 ocaml-multicore/eio#651). - Remove default backtrace from `Switch.fail` (@talex5 ocaml-multicore/eio#664). Documentation: - Organise eio.mli better (@talex5 ocaml-multicore/eio#667). - Fix quoting of quotes in process error messages (@talex5 ocaml-multicore/eio#666, reviewed by @SGrondin). - Mention Path module in File and Fs documentation (@talex5 ocaml-multicore/eio#659, requested by @clecat). - Minor documentation updates (@SGrondin @talex5 ocaml-multicore/eio#670). Build / internals: - Allow closing synchronous streams (@talex5 ocaml-multicore/eio#641, reviewed by @SGrondin). This isn't currently exposed in the public interface. - Fix non-idempotent tests (@SGrondin ocaml-multicore/eio#662). - eio_windows: add explicit fmt dependency (@talex5 ocaml-multicore/eio#643).
By default,
Flow.copy
creates a 4KB buffer and copies the data through that. However, if the source of the copy is a buffered reader then it is much more efficient to use its buffer directly.This updates the flow you get from
Buf_read.as_flow
to offer this optimisation, and also updates the eio_posix backend's flow to use this optimisation when available (eio_linux already supported this).Detected in a benchmark by @leostera.
Possibly we should increase the default buffer size too.
This PR is made of two commits. The first just adds a benchmark to show the effect of the change. On my Linux machine, I get: