Pavel Emelianov [xemul@xxxxx] wrote:
| > Index: lx26-21-mm2/kernel/pid.c
| > ===================================================================
| > --- lx26-21-mm2.orig/kernel/pid.c 2007-05-22 16:59:46.000000000 -0700
| > +++ lx26-21-mm2/kernel/pid.c 2007-05-22 17:06:48.000000000 -0700
| > @@ -216,6 +216,10 @@ fastcall void free_pid(struct pid *pid)
| > /* We can be called with write_lock_irq(&tasklist_lock) held */
| > unsigned long flags;
| >
| > + /* check this here to keep copy_process() cleaner */
| > + if (unlikely(pid == &init_struct_pid))
| > + return;
| > +
|
| This looks ugly to me.
I agree about the ugly part :-) but we need to distinguish
between idle thread and normal thread at some point in do_fork().
| That's the same as if we put
| if (ns == &init_pid_ns)
| return;
| in put_pid_ns() call.
|
| Such small struts of their own do not introduce any noticeable
| effect, but when we have them in many places (and on fast patsh
| like alloc_pid()) the performance hurts...
I agree and we have been trying to keep the impact as low as possible.
|
|
| > spin_lock_irqsave(&pidmap_lock, flags);
| > hlist_del_rcu(&pid->pid_chain);
| > spin_unlock_irqrestore(&pidmap_lock, flags);
| > @@ -224,12 +228,16 @@ fastcall void free_pid(struct pid *pid)
| > call_rcu(&pid->rcu, delayed_put_pid);
| > }
| >
| > -struct pid *alloc_pid(void)
| > +struct pid *alloc_pid(enum copy_process_type copy_src)
| > {
| > struct pid *pid;
| > enum pid_type type;
| > int nr = -1;
| >
| > + /* check this here to keep copy_process() cleaner */
| > + if (unlikely(copy_src == COPY_IDLE_PROCESS))
| > + return &init_struct_pid;
| > +
| > pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
| > if (!pid)
| > goto out;
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| >
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