diff options
| -rw-r--r-- | common/uapi/conf.c | 6 | ||||
| -rw-r--r-- | common/uapi/ipc.c | 13 | ||||
| -rw-r--r-- | include/kmi/conf.h | 17 |
3 files changed, 21 insertions, 15 deletions
diff --git a/common/uapi/conf.c b/common/uapi/conf.c index ba48d0f..ea06e06 100644 --- a/common/uapi/conf.c +++ b/common/uapi/conf.c @@ -86,8 +86,8 @@ SYSCALL_DEFINE2(conf_set)(struct tcb *t, sys_arg_t param, sys_arg_t val) break; case CONF_CALL_STACK: - size = align_up(val, RPC_STACK_RATIO * BASE_PAGE_SIZE); - if (size < __rpc_stack_size * RPC_STACK_RATIO) + size = align_up(val, BASE_PAGE_SIZE); + if (size < __rpc_stack_size) return_args(t, SYS_RET1(ERR_MISC)); __call_stack_size = size; @@ -95,7 +95,7 @@ SYSCALL_DEFINE2(conf_set)(struct tcb *t, sys_arg_t param, sys_arg_t val) case CONF_RPC_STACK: size = align_up(val, BASE_PAGE_SIZE); - if (size > __call_stack_size / RPC_STACK_RATIO) + if (size > __call_stack_size) return_args(t, SYS_RET1(ERR_MISC)); __rpc_stack_size = size; diff --git a/common/uapi/ipc.c b/common/uapi/ipc.c index 1d48f71..9cbdce8 100644 --- a/common/uapi/ipc.c +++ b/common/uapi/ipc.c @@ -36,6 +36,11 @@ static void mark_rpc_inaccessible(struct tcb *t, vm_t start, vm_t end) */ static void mark_rpc_accessible(struct tcb *t, vm_t start, vm_t end) { + /** @todo this could still be optimized with arch-specific stuff I would + * imagine, as set_vpage_flags() has to traverse the whole tree for each + * page to mark. Instead it should be possible to mark the pages + * continuously once they've been traversed once. Or maybe even keep + * around a pointer to where the last stack left off? */ size_t page_size = BASE_PAGE_SIZE; size_t size = end - start; size_t pages = size / page_size; @@ -43,7 +48,7 @@ static void mark_rpc_accessible(struct tcb *t, vm_t start, vm_t end) set_vpage_flags(t->rpc.vmem, start + pages * page_size, VM_U); } -/** Structure for maintaingin the required context data for an rpc call. */ +/** Structure for maintaining the required context data for an rpc call. */ struct call_ctx { /** Execution continuation point. */ vm_t exec; @@ -189,10 +194,14 @@ static void leave_rpc(struct tcb *t, struct sys_ret a) */ static bool enough_rpc_stack(struct tcb *t) { + /* get top of call stack */ vm_t top = RPC_STACK_BASE + __call_stack_size; + /* get start of the next rpc stack instance */ vm_t rpc_stack = t->rpc_stack + BASE_PAGE_SIZE; - return top - rpc_stack >= __call_stack_size / RPC_STACK_RATIO; + /* if we can still fit an rpc stack into the call stack, we can safely + * do the migration. */ + return top - rpc_stack >= __rpc_stack_size; } /** diff --git a/include/kmi/conf.h b/include/kmi/conf.h index 84b9f06..8e33a5f 100644 --- a/include/kmi/conf.h +++ b/include/kmi/conf.h @@ -24,6 +24,13 @@ extern size_t __thread_stack_size; /** * Provides access to the runtime global parameter. * Must be at most RPC_STACK_TOP - RPC_STACK_BASE. + * Essentially, each thread gets allocated this many bytes of total stack space + * that will be used during thread migrations. Each migration instance may at + * most take up __rpc_stack_size bytes, and during a thread migration the + * currently available free stack space is checked. + * + * Previous instances are unmapped, making them unaccessible to the current + * instance. * * \see __thread_stack_size. * \global @@ -35,18 +42,8 @@ extern size_t __call_stack_size; * Provides access to the runtime global parameter. This sets the maximum size * a single rpc stack instance can be. * - * Must be at most a fourth of \ref __call_stack_size? - * (that way we can maybe pretty quickly check that we're running out of memory - * for stack stuff and can return an error about it) - * * \global */ extern size_t __rpc_stack_size; -/** - * Convenience macro for requirement of ratio between \ref __rpc_stack_size and - * \ref __call_stack_size. - */ -#define RPC_STACK_RATIO 4 - #endif /* KMI_CONF_H */ |