On Tue, Jul 25, 2017 at 10:50:13PM +0000, Mathieu Desnoyers wrote: > This would implement a MEMBARRIER_CMD_PRIVATE_EXPEDITED (or such) flag > for expedited process-local effect. This differs from the "SHARED" flag, > since the SHARED flag affects threads accessing memory mappings shared > across processes as well. > > I wonder if we could create a MEMBARRIER_CMD_SHARED_EXPEDITED behavior > by iterating on all memory mappings mapped into the current process, > and build a cpumask based on the union of all mm masks encountered ? > Then we could send the IPI to all cpus belonging to that cpumask. Or > am I missing something obvious ?
I would readily object to such a beast. You far too quickly end up having to IPI everybody because of some stupid shared map or something (yes I know, normal DSOs are mapped private). The whole private_expedited is only palatable because we can only hinder our own threads (much).
