> On 01.07.2021., at 11:12, Benoit Ganne (bganne) via lists.fd.io > <bganne=cisco....@lists.fd.io> wrote: > >> Yes, allowing dynamic heap growth sounds like it could be better. >> Alternatively... if memory allocations could fail and something more >> graceful than VPP exiting could occur, that may also be better. E.g. if >> I'm adding a route and try to allocate a counter for it and that fails, it >> would be better to refuse to add the route than to exit and take the >> network down. >> >> I realize that neither of those options is easy to do btw. I'm just trying >> to figure out how to make it easier and more forgiving for users to set up >> their configuration without making them learn about various memory >> parameters. > > Understood, but setting a very high default will just make users of smaller > config puzzled too 😊 and I think changing all memory allocation callsites to > check for NULL would be a big paradigm change in VPP. > That's why I think a dynamically growing heap might be better but I do not > really know what would be the complexity. > That said, you can probably change the default in your own build and that > should work. >
Fully agree wirth Benoit. We should not increase heap size default value. Things are actually a bit more complicated. For performance reasons people should use hugepages whenever they are available, but they are also not default. When hugepages are used all pages are immediately backed with physical memory. So different use cases require different heap configurations and end user needs to tune that. Same applies for other things like stats segment page size which again may impact forwarding performance significantly. If messing with startup.conf is too complicated for end user, some nice configuration script may be helpful. Or just throwing few startup.confs into extras/startup_configs. Dynamic heap is possible, but not straight forward, as at some places we use offsets to the start of the heap, so additional allocation cannot be anywhere. Also it will not help in some cases, i.e. when 1G hugepage is used for heap, growing up to 2G will fail if 2nd 1G page is not pre-allocated. — Damjan
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