SAP Note 21893 - R/3 does not start,dev_disp:fork(11: No more proc)

Symptom:

R/3 does not start. All work processes and the dispatcher terminate immediately.
The developer trace dev_disp (directory: /usr/sap//DVEBMGS00/work)
contains the following error messages:

*** ERROR => DpWpCreate: fork (11: No more processes) [dpuxdisp 0472]
***LOG Q0I=> DpWpCreate, fork ( fork 11) [dpuxdisp 0473]
*** ERROR => DpWpDynCreate: DpWpCreate [dpuxdisp 0245]
*** ERROR => DpProcCreate: DpWpDynCreate [dpxxdisp 5319]

or:
*** ERROR => DpWpCreate: fork (35: Operation would block) [dpuxdisp ...
***LOG Q0I=> DpWpCreate, fork ( fork 35) [dpuxdisp 0498]
*** ERROR => DpWpDynCreate: DpWpCreate [dpuxdisp 0242]
*** ERROR => DpProcCreate: DpWpDynCreate [dpxxdisp 5411]

or also:
*** ERROR => e=28 semget(30089,1,2047) (28: No space left on device)
[evtux.c 0859]
*** ERROR => DpWpConnect: EvtCreate (rc=1) [dpxxdisp 5115]
*** ERROR => DpSapEnvInit: DpWpConnect [dpxxdisp 3359]
*** EvtClose: Invalid Event Handle [evtux.c 1166]

Additional key words

startsap sapstart startr3 r3start

Cause and prerequisites

Case 1, 2: The header file /usr/include/sys/errno.h contains the key
term "EAGAIN" and "EWOULDBLOCK"
for error numbers 11 and 35. The man fork shows the
meaning of key word "EAGAIN"
a.) Too little swap space
b.) Kernel parameter "Max. number of processes per user"
is too small.

Case 2: Kernel parameter group "Semaphores" does not correspond to
the SAP recommendations.

Solution
Make sure the kernel parameters recommended by SAP are used (see Installation Guide).