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thread API & CPU session: accounting of CPU quota

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In the init configuration one can configure the donation of CPU time via
'resource' tags that have the attribute 'name' set to "CPU" and the
attribute 'quantum' set to the percentage of CPU quota that init shall
donate. The pattern is the same as when donating RAM quota.

! <start name="test">
!   <resource name="CPU" quantum="75"/>
! </start>

This would cause init to try donating 75% of its CPU quota to the child
"test".  Init and core do not preserve CPU quota for their own
requirements by default as it is done with RAM quota.

The CPU quota that a process owns can be applied through the thread
constructor. The constructor has been enhanced by an argument that
indicates the percentage of the programs CPU quota that shall be granted
to the new thread. So 'Thread(33, "test")' would cause the backing CPU
session to try to grant 33% of the programs CPU quota to the thread
"test". By now, the CPU quota of a thread can't be altered after
construction. Constructing a thread with CPU quota 0 doesn't mean the
thread gets never scheduled but that the thread has no guaranty to receive
CPU time. Such threads have to live with excess CPU time.

Threads that already existed in the official repositories of Genode were
adapted in the way that they receive a quota of 0.

This commit also provides a run test 'cpu_quota' in base-hw (the only
kernel that applies the CPU-quota scheme currently). The test basically
runs three threads with different physical CPU quota. The threads simply
count for 30 seconds each and the test then checks wether the counter
values relate to the CPU-quota distribution.

fix #1275
This commit is contained in:
Martin Stein
2014-10-16 11:15:46 +02:00
committed by Christian Helmuth
parent f60e2af21f
commit 8f9355b360
79 changed files with 898 additions and 187 deletions
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13
repos/base-linux/include/linux_cpu_session/client.h
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@ -24,8 +24,8 @@ namespace Genode {
explicit Linux_cpu_session_client(Capability<Linux_cpu_session> session)
: Rpc_client<Linux_cpu_session>(session) { }
Thread_capability create_thread(Name const &name, addr_t utcb = 0) {
return call<Rpc_create_thread>(name, utcb); }
Thread_capability create_thread(size_t, Name const &name, addr_t utcb = 0) {
return call<Rpc_create_thread>(0, name, utcb); }
Ram_dataspace_capability utcb(Thread_capability thread) {
return call<Rpc_utcb>(thread); }
@ -78,6 +78,15 @@ namespace Genode {
Dataspace_capability trace_policy(Thread_capability thread) {
return call<Rpc_trace_policy>(thread); }
int ref_account(Cpu_session_capability session) {
return call<Rpc_ref_account>(session); }
int transfer_quota(Cpu_session_capability session, size_t amount) {
return call<Rpc_transfer_quota>(session, amount); }
size_t quota() { return call<Rpc_quota>(); }
size_t used() { return call<Rpc_used>(); }
/*****************************
* Linux-specific extension **