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Florian Westphal says: ==================== xfrm: remove flow cache After RCU-ification of ipsec packet path there are no major scalability issues anymore without flow cache. We still incur a performance hit, which comes mostly from the extra xfrm dst allocation/freeing. The last patch in the series adds a simple percpu cache to avoid the extra allocation if a packet matched the same policies as last one. The main concern with this is that we will see performance drops, especially with large numbers of policies/SAs. However, during hallway discussions at nfws 2017 it seemed the issues with flow caching outweight the removal downsides, and that it might be best to just 'remove it' and see where the practical issues (if any) will appear. It should now be possible to also remove the genid member in the policies as we don't hold bundles for prolonged time anymore, but I think this change is controversial (and intrusive) enough as-is, so defer that to a later point in time. Changes since last rfc: - fix build failures due to implicit interrupt.h includes - rework last patch (pcpu cache): * avoid xchg() * check policies for walk.dead = 1 instead of more costly bundle_ok(). * flush pcpu bundles when sa/policies get removed, to allow module references to go away (suggested by Ilan Tayari) ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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.