Relax requirement to run as root and mlock() less memory
#417
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Snabb Switch previously called mlockall() to force all memory in the process address space to be locked to its physical location. This made it possible to use all memory for DMA, including memory mapped from virtual machines. This had several side-effects: * Prevent Snabb Switch from being swapped out. (Nice?) * Prevent VMs that we serve from being swapped out. (Overkill?) * Requires root permissions at startup. (Overkill?) The new behavior is to individually mlock() the HugeTLB pages that we allocate for DMA. The rest of the memory - Snabb Switch and VMs - is left unlocked. This is feasible now that we only do DMA within this memory. This also allows us to defer the root-privileged system call until we need DMA memory, which may not happen for ceratin applications.
Wait until the first packet is needed to allocate the memory.
Certain Snabb programs don't require root permissions. The ones that do will need to check for them when system calls fail unexpectedly.
Use ljsyscall's geteuid() via a new library function:
lib.root_check()
lukego
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dpino
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Aug 31, 2016
Change lwAFTR counters location
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Allow Snabb Switch to run as a non-root user unless/until privileged operations are required e.g. access to hardware and DMA.
These privileged operations are deferred from startup:
mlockall()while loading the memory module, but now we callmlock()individually on the HugeTLBs we allocate for DMA.