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when the packet or frag size is small, it causes both security and performance issue. As dma can't map sub-page, this means some extra kernel data is visible to devices. On the other hand, the overhead of dma map and unmap is huge when IOMMU is on. So add a queue based tx shared bounce buffer to memcpy the small packet when the len of the xmitted skb is below tx_copybreak. Add tx_spare_buf_size module param to set the size of tx spare buffer, and add set/get_tunable to set or query the tx_copybreak. The throughtput improves from 30 Gbps to 90+ Gbps when running 16 netperf threads with 32KB UDP message size when IOMMU is in the strict mode(tx_copybreak = 2000 and mtu = 1500). Suggested-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.