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Re: 8.0 performance issue when running build.sh?





On Aug 6, 2018, at 12:17 PM, Rhialto <rhialto%falu.nl@localhost> wrote:

21.96   24626  82447.93 kernel_lock            ip_slowtimo+1a

The work that's happening here looks like a scalability nightmare., regardless of holding the kernel lock or not.  A couple of things:

1- It should do a better job of determining if there's any work that it actually has to do.  As it is, it's going to lock the kernel_lock and traverse all of the buckets in a hash table even if there aren't any entries in it.  Even in the NET_MPSAFE scenario, that's pointless work.

2- The kernel_lock, by its nature, is the lock-of-last-resort, and code needs to be doing everything it can to defer taking that lock until it is deemed absolutely necessary.  Even in the not-NET_MPSAFE scenario, there should be a way to determine that IP fragment expiration processing needs to actually occur before taking the kernel_lock.

-- thorpej



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