Revision 4fc216649ddb40763963140eac3eb95890b32486 authored by Cheng Chang on 20 March 2020, 23:15:40 UTC, committed by Facebook GitHub Bot on 20 March 2020, 23:33:26 UTC
Summary: By supporting direct IO in RandomAccessFileReader::MultiRead, the benefits of parallel IO (IO uring) and direct IO can be combined. In direct IO mode, read requests are aligned and merged together before being issued to RandomAccessFile::MultiRead, so blocks in the original requests might share the same underlying buffer, the shared buffers are returned in `aligned_bufs`, which is a new parameter of the `MultiRead` API. For example, suppose alignment requirement for direct IO is 4KB, one request is (offset: 1KB, len: 1KB), another request is (offset: 3KB, len: 1KB), then since they all belong to page (offset: 0, len: 4KB), `MultiRead` only reads the page with direct IO into a buffer on heap, and returns 2 Slices referencing regions in that same buffer. See `random_access_file_reader_test.cc` for more examples. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6446 Test Plan: Added a new test `random_access_file_reader_test.cc`. Reviewed By: anand1976 Differential Revision: D20097518 Pulled By: cheng-chang fbshipit-source-id: ca48a8faf9c3af146465c102ef6b266a363e78d1
1 parent 5fd152b
CONTRIBUTING.md
# Contributing to RocksDB
## Code of Conduct
The code of conduct is described in [`CODE_OF_CONDUCT.md`](CODE_OF_CONDUCT.md)
## Contributor License Agreement ("CLA")
In order to accept your pull request, we need you to submit a CLA. You
only need to do this once, so if you've done this for another Facebook
open source project, you're good to go. If you are submitting a pull
request for the first time, just let us know that you have completed
the CLA and we can cross-check with your GitHub username.
Complete your CLA here: <https://code.facebook.com/cla>
If you prefer to sign a paper copy, we can send you a PDF. Send us an
e-mail or create a new github issue to request the CLA in PDF format.
Computing file changes ...
