this adds a debug configure switch to enable monitoring of the
maximum used stack size by all coroutines.
Signed-off-by: Peter Lieven <p...@kamp.de>
---
configure | 18 ++++++++++++++++++
util/coroutine-ucontext.c | 40 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/configure b/configure
index 5929aba..82bcc25 100755
--- a/configure
+++ b/configure
@@ -296,6 +296,7 @@ libiscsi=""
libnfs=""
coroutine=""
coroutine_pool=""
+coroutine_stack_size_debug="no"
seccomp=""
glusterfs=""
glusterfs_xlator_opt="no"
@@ -1004,6 +1005,8 @@ for opt do
;;
--enable-coroutine-pool) coroutine_pool="yes"
;;
+ --enable-coroutine-stack-size-debug) coroutine_stack_size_debug="yes"
+ ;;
--disable-docs) docs="no"
;;
--enable-docs) docs="yes"
@@ -1361,6 +1364,8 @@ disabled with --disable-FEATURE, default is enabled if
available:
(for reading bzip2-compressed dmg images)
seccomp seccomp support
coroutine-pool coroutine freelist (better performance)
+ coroutine-stack-size-debug
+ report coroutine max stack usage (only for debugging)
glusterfs GlusterFS backend
archipelago Archipelago backend
tpm TPM support
@@ -4298,6 +4303,15 @@ fi
if test "$coroutine" = "gthread" -a "$coroutine_pool" = "yes"; then
error_exit "'gthread' coroutine backend does not support pool (use
--disable-coroutine-pool)"
fi
+if test "$coroutine_stack_size_debug" = "yes"; then
+ if test "$coroutine" != "ucontext"; then
+ error_exit "coroutine stack size debugging currently only works with
ucontext"
+ fi
+ if test "$coroutine_pool" = "yes"; then
+ echo "WARN: disabling coroutine pool for stack size debugging"
+ coroutine_pool=no
+ fi
+fi
##########################################
# check if we have open_by_handle_at
@@ -4866,6 +4880,7 @@ echo "QGA MSI support $guest_agent_msi"
echo "seccomp support $seccomp"
echo "coroutine backend $coroutine"
echo "coroutine pool $coroutine_pool"
+echo "coroutine stack size debug $coroutine_stack_size_debug"
echo "GlusterFS support $glusterfs"
echo "Archipelago support $archipelago"
echo "gcov $gcov_tool"
@@ -5335,6 +5350,9 @@ if test "$coroutine_pool" = "yes" ; then
else
echo "CONFIG_COROUTINE_POOL=0" >> $config_host_mak
fi
+if test "$coroutine_stack_size_debug" = "yes" ; then
+ echo "CONFIG_COROUTINE_STACK_SIZE_DEBUG=y" >> $config_host_mak
+fi
if test "$open_by_handle_at" = "yes" ; then
echo "CONFIG_OPEN_BY_HANDLE=y" >> $config_host_mak
diff --git a/util/coroutine-ucontext.c b/util/coroutine-ucontext.c
index 841e7db..27c61f3 100644
--- a/util/coroutine-ucontext.c
+++ b/util/coroutine-ucontext.c
@@ -31,6 +31,10 @@
#include <valgrind/valgrind.h>
#endif
+#ifdef CONFIG_COROUTINE_STACK_SIZE_DEBUG
+#include "qemu/error-report.h"
+#endif
+
typedef struct {
Coroutine base;
void *stack;
@@ -48,6 +52,10 @@ typedef struct {
static __thread CoroutineUContext leader;
static __thread Coroutine *current;
+#ifdef CONFIG_COROUTINE_STACK_SIZE_DEBUG
+static uint32_t max_stack_usage;
+#endif
+
/*
* va_args to makecontext() must be type 'int', so passing
* the pointer we need may require several int args. This
@@ -88,6 +96,9 @@ Coroutine *qemu_coroutine_new(void)
ucontext_t old_uc, uc;
sigjmp_buf old_env;
union cc_arg arg = {0};
+#ifdef CONFIG_COROUTINE_STACK_SIZE_DEBUG
+ void *ptr;
+#endif
/* The ucontext functions preserve signal masks which incurs a
* system call overhead. sigsetjmp(buf, 0)/siglongjmp() does not
@@ -118,6 +129,13 @@ Coroutine *qemu_coroutine_new(void)
co->stack = g_malloc(stack_size);
#endif
+#ifdef CONFIG_COROUTINE_STACK_SIZE_DEBUG
+ for (ptr = co->stack + getpagesize();
+ ptr < co->stack + COROUTINE_STACK_SIZE; ptr += sizeof(u_int32_t)) {
+ *(u_int32_t *)ptr = 0xdeadbeaf;
+ }
+#endif
+
co->base.entry_arg = &old_env; /* stash away our jmp_buf */
uc.uc_link = &old_uc;
@@ -161,6 +179,20 @@ void qemu_coroutine_delete(Coroutine *co_)
{
CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
+#ifdef CONFIG_COROUTINE_STACK_SIZE_DEBUG
+ void *ptr;
+ for (ptr = co->stack + getpagesize();
+ ptr < co->stack + COROUTINE_STACK_SIZE; ptr += sizeof(u_int32_t)) {
+ if (*(u_int32_t *)ptr != 0xdeadbeaf) {
+ break;
+ }
+ }
+ /* we only want to estimate the max stack usage, the OR will overestimate
+ * the stack usage, but this is ok here and avoids the usage of a mutex */
+ atomic_or(&max_stack_usage,
+ COROUTINE_STACK_SIZE - (uintptr_t) (ptr - co->stack));
+#endif
+
#ifdef CONFIG_VALGRIND_H
valgrind_stack_deregister(co);
#endif
@@ -210,3 +242,11 @@ bool qemu_in_coroutine(void)
{
return current && current->caller;
}
+
+#ifdef CONFIG_COROUTINE_STACK_SIZE_DEBUG
+static void __attribute__((destructor)) print_max_stack_usage(void)
+{
+ error_report("coroutine-ucontext: max stack usage was less or equal to "
+ "%"PRIu32" bytes.", max_stack_usage);
+}
+#endif
--
1.9.1
