On 06/30/2011 06:54 PM, Peter Zijlstra wrote:
On Wed, 2011-06-29 at 11:29 -0400, Glauber Costa wrote:
+static noinline bool touch_steal_time(int is_idle)
That noinline is very unlucky there,
+{
+ u64 steal, st = 0;
+
+ if (static_branch(¶virt_steal_enabled)) {
+
+ steal = paravirt_steal_clock(smp_processor_id());
+
+ steal -= this_rq()->prev_steal_time;
+
+ st = steal_ticks(steal);
+ this_rq()->prev_steal_time += st * TICK_NSEC;
+
+ if (is_idle || st == 0)
+ return false;
+
+ account_steal_time(st);
+ return true;
+ }
+ return false;
+}
+
static void update_rq_clock_task(struct rq *rq, s64 delta)
{
s64 irq_delta;
@@ -3716,6 +3760,9 @@ void account_user_time(struct task_struct *p,
cputime_t cputime,
struct cpu_usage_stat *cpustat =&kstat_this_cpu.cpustat;
cputime64_t tmp;
+ if (touch_steal_time(0))
+ return;
Means we have an unconditional call here, even if the static_branch() is
patched out.
Ok.
I was under the impression that the proper use of jump labels required
each label to be tied to a single location. If we make it inline, the
same key would point to multiple locations, and we would have trouble
altering all of the locations. I might be wrong, of course. Isn't it the
case?
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