forked from Minki/linux
mainlining shenanigans
43be3a3c65
Arjun Roy says: ==================== Perf. optimizations for TCP Recv. Zerocopy This patchset contains several optimizations for TCP Recv. Zerocopy. Summarized: 1. It is possible that a read payload is not exactly page aligned - that there may exist "straggler" bytes that we cannot map into the caller's address space cleanly. For this, we allow the caller to provide as argument a "hybrid copy buffer", turning getsockopt(TCP_ZEROCOPY_RECEIVE) into a "hybrid" operation that allows the caller to avoid a subsequent recvmsg() call to read the stragglers. 2. Similarly, for "small" read payloads that are either below the size of a page, or small enough that remapping pages is not a performance win - we allow the user to short-circuit the remapping operations entirely and simply copy into the buffer provided. Some of the patches in the middle of this set are refactors to support this "short-circuiting" optimization. 3. We allow the user to provide a hint that performing a page zap operation (and the accompanying TLB shootdown) may not be necessary, for the provided region that the kernel will attempt to map pages into. This allows us to avoid this expensive operation while holding the socket lock, which provides a significant performance advantage. With all of these changes combined, "medium" sized receive traffic (multiple tens to few hundreds of KB) see significant efficiency gains when using TCP receive zerocopy instead of regular recvmsg(). For example, with RPC-style traffic with 32KB messages, there is a roughly 15% efficiency improvement when using zerocopy. Without these changes, there is a roughly 60-70% efficiency reduction with such messages when employing zerocopy. ==================== Link: https://lore.kernel.org/r/20201202225349.935284-1-arjunroy.kdev@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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| include | ||
| init | ||
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| kernel | ||
| lib | ||
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| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.