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init: Transfer slack memory to children on demand

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This commit is contained in:
Norman Feske 2013-09-26 21:26:50 +02:00
parent 65c4246f95
commit 5caed68fe4
1 changed files with 43 additions and 2 deletions
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45
os/include/init/child.h
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@ -82,6 +82,18 @@ namespace Init {
}
/**
* Return amount of RAM that is currently unused
*/
static inline Genode::size_t avail_slack_ram_quota()
{
Genode::size_t const preserve = 128*1024;
Genode::size_t const avail = Genode::env()->ram_session()->avail();
return avail > preserve ? avail - preserve : 0;
}
inline Genode::size_t read_ram_quota(Genode::Xml_node start_node)
{
Genode::Number_of_bytes ram_quota = 0;
@ -103,8 +115,8 @@ namespace Init {
* our allocation of the child meta data from the heap.
* Hence, we preserve some of our own quota.
*/
if (ram_quota > Genode::env()->ram_session()->avail() - 128*1024) {
ram_quota = Genode::env()->ram_session()->avail() - 128*1024;
if (ram_quota > avail_slack_ram_quota()) {
ram_quota = avail_slack_ram_quota();
if (config_verbose)
Genode::printf("Warning: Specified quota exceeds available quota.\n"
" Proceeding with a quota of %zd bytes.\n",
@ -704,6 +716,35 @@ namespace Init {
return true;
}
void resource_request(Genode::Parent::Resource_args const &args)
{
Genode::printf("child \"%s\" requests resources: %s\n",
name(), args.string());
Genode::size_t const requested_ram_quota =
Genode::Arg_string::find_arg(args.string(), "ram_quota")
.ulong_value(0);
if (avail_slack_ram_quota() < requested_ram_quota) {
PERR("Cannot respond to resource request - out of memory");
return;
}
/*
* XXX Synchronize quota transfers from/to env()->ram_session()
*
* If multiple children issue concurrent resource requests, the
* value reported by 'avail_slack_ram_quota' may be out of date
* when calling 'transfer_quota'.
*/
Genode::env()->ram_session()->transfer_quota(_resources.ram.cap(),
requested_ram_quota);
/* wake up child that was starved for resources */
_child.notify_resource_avail();
}
Genode::Native_pd_args const *pd_args() const { return &_pd_args; }
};
}