Re: [tip:tracing/urgent] tracing: Allocate the ftrace eventprofile buffer dynamically

From: Ingo Molnar
Date: Sat Sep 19 2009 - 12:53:20 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Sat, 2009-09-19 at 07:58 +0000, tip-bot for Frederic Weisbecker
> wrote:
>
> > +/*
> > + * We can't use a size but a type in alloc_percpu()
> > + * So let's create a dummy type that matches the desired size
> > + */
> > +typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
> > +
> > static int ftrace_profile_enable_event(struct ftrace_event_call *event)
> > {
> > + char *buf;
> > + int ret;
> > +
> > if (atomic_inc_return(&event->profile_count))
> > return 0;
> >
> > - return event->profile_enable();
> > + buf = (char *)alloc_percpu(profile_buf_t);
> > + if (!buf)
> > + return -ENOMEM;
>
> Ingo,
>
> Did you pull in the version that allocates a buffer for each event? I
> thought Frederic made just a global per cpu buffer that all events can
> use. The buffer is just a temporary storage that will be too big to
> put on the stack.

Yeah - i had v1 briefly - then pulled in the later (v3) one.

Ingo
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