I'm not certain what prompted performing the check in ibv_fork_init. However, it seems to me that hugepages registration support is orthogonal to forking. Given what the environment variable addresses and the fact that the variable is only read in ibv_fork_init, I would wonder if the application would crash if it did NOT call ibv_fork_init -- even if it wasn't planning to fork.
--- James Swaro Cray Inc. On 4/10/19, 10:03 AM, "Jason Gunthorpe" <[email protected]> wrote: On Wed, Apr 10, 2019 at 02:36:53PM +0000, James Swaro wrote: > I’d be interested in exposing an environment variable, flag, or general > tunable in libfabric for applications to indicate whether they want to > use huge pages. Using the verbs provider on an internal development > system, I’ve run into an issue where use of huge pages makes the memory > registration function fail unless RDMAV_HUGEPAGES_SAFE is set. > See [1]https://lists.openfabrics.org/pipermail/ewg/2010-July/015609.htm > l for context. Oh gross, this should just be fixed in verbs to not require the ugly environment variable in the first place. > general, if necessary. For verbs, use of the RDMAV_HUGEPAGES_SAFE > variable tends to impact performance mostly after the rendezvous > threshold. After reaching the rendezvous threshold, latency for data > transfer operations appears to increase by a factor of ten. If the app isn't forking it shouldn't even be calling ibv_fork_init in the first place, which solves both problems. Jason _______________________________________________ ofiwg mailing list [email protected] https://lists.openfabrics.org/mailman/listinfo/ofiwg
