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Karel Rericha reported that in his test case, ICMP packets going through boxes had normally about 5ms latency. But when running nft, actually listing the sets with interval flags, latency would go up to 30-100ms. This was observed when router throughput is from 600Mbps to 2Gbps. This is because we use a single global spinlock to protect the whole rbtree sets, so "dumping sets" will race with the "key lookup" inevitably. But actually they are all _readers_, so it's ok to convert the spinlock to rwlock to avoid competition between them. Also use per-set rwlock since each set is independent. Reported-by: Karel Rericha <karel@unitednetworks.cz> Tested-by: Karel Rericha <karel@unitednetworks.cz> Signed-off-by: Liping Zhang <zlpnobody@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.