Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor | Date | Wed, 29 Jul 2020 08:36:33 +0000 |
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From: Madhavan T. Venkataraman > Sent: 28 July 2020 19:52 ... > trampfd faults are instruction faults that go through a different code path than > the one that calls handle_mm_fault(). Perhaps, it is the handle_mm_fault() that > is time consuming. Could you clarify?
Given that the expectation is a few instructions in userspace (eg to pick up the original arguments for a nested call) the (probable) thousands of clocks taken by entering the kernel (especially with page table separation) is a massive delta.
If entering the kernel were cheap no one would have added the DSO functions for getting the time of day.
David
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