On Thu 24 May 2018 at 23:34, Cong Wang <xiyou.wangcong@xxxxxxxxx> wrote: > On Mon, May 14, 2018 at 7:27 AM, Vlad Buslov <vladbu@xxxxxxxxxxxx> wrote: >> Currently, all netlink protocol handlers for updating rules, actions and >> qdiscs are protected with single global rtnl lock which removes any >> possibility for parallelism. This patch set is a first step to remove >> rtnl lock dependency from TC rules update path. It updates act API to >> use atomic operations, rcu and spinlocks for fine-grained locking. It >> also extend API with functions that are needed to update existing >> actions for parallel execution. > > Can you give a summary here for what and how it is achieved? Got it, will expand cover letter in V2 with summary. > > You said this is the first step, what do you want to achieve in this > very first step? And how do you achieve it? Do you break the RTNL But aren't this questions answered in paragraph you quoted? What: Change act API to not rely on one-big-global-RTNL-lock and to use more fine-grained synchronization methods to allow safe concurrent execution. How: Refactor act API code to use atomics, rcu and spinlocks, etc. for protecting shared data structures, add new functions required to update specific actions implementation for parallel execution. (step 2) If you feel that this cover letter is too terse, I will add outline of changes in V2. > lock down to, for a quick example, a per-device lock? Or perhaps you > completely remove it because of what reason? I want to remove RTNL _dependency_ from act API data structures and code. I probably should me more specific in this case: Florian recently made a change that allows registering netlink protocol handlers with flag RTNL_FLAG_DOIT_UNLOCKED. Handlers registered with this flag are called without RTNL taken. My end goal is to have rule update handlers(RTM_NEWTFILTER, RTM_DELTFILTER, etc.) to be registered with UNLOCKED flag to allow parallel execution. I do not intend to globally remove or break RTNL. > > I go through all the descriptions of your 14 patches (but not any code), > I still have no clue how you successfully avoid RTNL. Please don't > let me read into your code to understand that, there must be some > high-level justification on how it works. Without it, I don't event want > to read into the code. On internal code review I've been asked not to duplicate info from commit messages in cover letter, but I guess I can expand it with some high level outline in V2. > > Thanks. Thank you for your feedback! -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
