minimizing physical memory budget
Steven Harp
steven.harp at adventiumlabs.com
Wed Jun 27 23:59:24 CEST 2018
What are the main factors in estimating the minimum RAM
quantum needed by a component? (Excluding for this discussion
any dynamic allocation an application might perform.)
The Genode Foundations book (18.05) suggests that if no quantum
is specified, "init has a reasonable default of 160K (on 32 bit)".
Experimentally, it seems like even the most modest components
need more. For example the client side of the hello_tutorial,
essentially 5 source lines and a 20K stripped ELF binary, seems to
need about 500K on a 32-bit x86 system.
At quantum="480K" for hello_client, one sees:
Warning: PD (init -> hello_client) RAM limit (used=380K, limit=394587)
exceeded during transfer_quota(6K)
(and the test hangs.)
At 425K, the result is:
[init] child "hello_client" requests resources: ram_quota=69632
page fault, pd='init -> hello_client' thread='hello_client' cpu=0 ip=0xa2adc address=0xa00fde50 stack pointer=0x0 qualifiers=0x6 irUWp reason=1
At 300K, we see:
[init] Error: allocation of read-write segment failed
[init] Error: hello_client: out of RAM during ELF loading
Is there a way to tweak component compilation/linking parameters to
minimize physical RAM required?
// Steve Harp
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