3af0356c16
We use lockless lists for the local and deferred task_work, which means that when we queue up events for processing, we ultimately process them in reverse order to how they were received. This usually doesn't matter, but for some cases, it does seem to make a big difference. Do the right thing and reverse the list before processing it, so that we know it's processed in the same order in which it was received. This makes a rather big difference for some medium load network tests, where consistency of performance was a bit all over the place. Here's a case that has 4 connections each doing two sends and receives: io_uring port=10002: rps:161.13k Bps: 1.45M idle=256ms io_uring port=10002: rps:107.27k Bps: 0.97M idle=413ms io_uring port=10002: rps:136.98k Bps: 1.23M idle=321ms io_uring port=10002: rps:155.58k Bps: 1.40M idle=268ms and after the change: io_uring port=10002: rps:205.48k Bps: 1.85M idle=140ms user=40ms io_uring port=10002: rps:203.57k Bps: 1.83M idle=139ms user=20ms io_uring port=10002: rps:218.79k Bps: 1.97M idle=106ms user=30ms io_uring port=10002: rps:217.88k Bps: 1.96M idle=110ms user=20ms io_uring port=10002: rps:222.31k Bps: 2.00M idle=101ms user=0ms io_uring port=10002: rps:218.74k Bps: 1.97M idle=102ms user=20ms io_uring port=10002: rps:208.43k Bps: 1.88M idle=125ms user=40ms using more of the time to actually process work rather than sitting idle. No effects have been observed at the peak end of the spectrum, where performance is still the same even with deep batch depths (and hence more items to sort). Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.