On 08/17/2018 12:45 PM, Davidlohr Bueso wrote: > Cc'ing Manfred. > > On Mon, 18 Jun 2018, Waiman Long wrote: > >> The maximum number of unique System V IPC identifiers was limited to >> 32k. That limit should be big enough for most use cases. >> >> However, there are some users out there requesting for more. To satisfy >> the need of those users, a new boot time kernel option "ipcmni_extend" >> is added to extend the IPCMNI value to 2M. This is a 64X increase which >> hopefully is big enough for them. > > Could you please provide more info on the need of these users and how > you came up with this new value (which just seems quite arbitrary)? > > Thanks, > Davidlohr Red Hat has a customer that is migrating from Solaris to Linux. Some of their applications just happen to use more than 32k of shared memory segments. I think Solaris allows up to 16M unique ID. Yes, the amount of increase is a bit arbitrary. I was trying to balance how many bits should be left for sequence number. Maybe I should just take 8 more bits for ID and leave 8 bits for sequence number to match Solaris. -Longman
