If the primary process dies: a) The memory does not go away, so the second process can still use it b) When restarting the primary process, you should restart it as a secondary one, to ensure it reattaches to memory properly instead of trying to re-initialize it.
Regards /Bruce > -----Original Message----- > From: Prashant Upadhyaya [mailto:prashant.upadhyaya at aricent.com] > Sent: Monday, November 25, 2013 4:08 AM > To: Richardson, Bruce; dev at dpdk.org > Subject: RE: Query regarding multiple processes in DPDK > > Hi Bruce, > > One more question -- > > Suppose the first instance comes up as primary and creates the mbuf pool > and rings etc. [ok] Now, the second instance comes up as secondary and > does the corresponding lookup functions [ok] Now the primary exits -- at > this point can the secondary still run with all the memory to which it had > done the lookup intact, or does the fact that primary died will lead to all > the > memory also taken away with it so that the secondary can no longer > function now ? > > Regards > -Prashant > > > -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Prashant > Upadhyaya > Sent: Friday, November 22, 2013 7:16 PM > To: Richardson, Bruce; dev at dpdk.org > Subject: Re: [dpdk-dev] Query regarding multiple processes in DPDK > > Thanks Bruce, I think your suggested example of multi_process answers my > questions. > > Regards > -Prashant > > > -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Prashant > Upadhyaya > Sent: Friday, November 22, 2013 7:10 PM > To: Richardson, Bruce; dev at dpdk.org > Subject: Re: [dpdk-dev] Query regarding multiple processes in DPDK > > Hi Bruce, > > Thanks. > > Regarding your comment -- > [BR] It will depend upon the application, but in most cases you probably > want to have slightly different code paths for primary and secondary > instances. For example, if a process is running as primary instance, it will > probably call rte_mempool_create or rte_ring_create. A secondary instance > which wants to use these should instead call rte_mempool_lookup and > rte_ring_lookup instead. > For an example of how to write the one binary to be used as both primary > and secondary process, I suggest looking at the symmetric_mp example > application in the examples/multi_process/ directory. > > I was really hoping that the --proc-type=auto, would make the DPDK > libraries internally resolving all this stuff, is that not the case ? I have > not > started reading the code for all this yet. > I must launch the same executable twice in my usecase. Even if the > executable code has to make different calls when it comes up as secondary, > is there a way for the usercode to know that it has really come up as > secondary when the --proc-type=auto is used ? > > Regards > -Prashant > > -----Original Message----- > From: Richardson, Bruce [mailto:bruce.richardson at intel.com] > Sent: Friday, November 22, 2013 7:02 PM > To: Prashant Upadhyaya; dev at dpdk.org > Subject: RE: Query regarding multiple processes in DPDK > > Hi Prashant > > > === > > The EAL also supports an auto-detection mode (set by EAL > > --proc-type=auto flag), whereby an Intel(r) DPDK process is started as > > a secondary instance if a primary instance is already running. > > === > > > > So does this mean that if I have a DPDK exe foo.out, then when I run > > the first instance of foo.out with -proc-type = auto, then foo.out > > will run as a primary process and when I spawn the second instance of > > foo.out (with first already running) again with -proc-type=auto, then > > this second instance automatically becomes secondary ? > [BR] Yes, that is the idea. > > > > > Also is there any user code initialization change required or exactly > > the same code will work for both the processes ? > [BR] It will depend upon the application, but in most cases you probably > want to have slightly different code paths for primary and secondary > instances. For example, if a process is running as primary instance, it will > probably call rte_mempool_create or rte_ring_create. A secondary instance > which wants to use these should instead call rte_mempool_lookup and > rte_ring_lookup instead. > For an example of how to write the one binary to be used as both primary > and secondary process, I suggest looking at the symmetric_mp example > application in the examples/multi_process/ directory. > > Regards, > /Bruce > > > > > > ========================================================== > ===================== > Please refer to http://www.aricent.com/legal/email_disclaimer.html > for important disclosures regarding this electronic communication. > ========================================================== > ===================== > > > > > ========================================================== > ===================== > Please refer to http://www.aricent.com/legal/email_disclaimer.html > for important disclosures regarding this electronic communication. > ========================================================== > ===================== > > > > > ========================================================== > ===================== > Please refer to http://www.aricent.com/legal/email_disclaimer.html > for important disclosures regarding this electronic communication. > ========================================================== > =====================
