2002-03-27 21:46:28

by Corey Minyard

[permalink] [raw]

Subject: [patch] Threads performance - allow signal handler to not call handler

---

--- ./arch/i386/kernel/signal.c.nocallhndlr Wed Mar 27 10:56:29 2002
+++ ./arch/i386/kernel/signal.c Wed Mar 27 11:04:45 2002
@@ -558,21 +558,24 @@
}
}

- /* Set up the stack frame */
- if (ka->sa.sa_flags & SA_SIGINFO)
- setup_rt_frame(sig, ka, info, oldset, regs);
- else
- setup_frame(sig, ka, oldset, regs);
-
if (ka->sa.sa_flags & SA_ONESHOT)
ka->sa.sa_handler = SIG_DFL;

- if (!(ka->sa.sa_flags & SA_NODEFER)) {
- spin_lock_irq(&current->sigmask_lock);
- sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
- sigaddset(&current->blocked,sig);
- recalc_sigpending(current);
- spin_unlock_irq(&current->sigmask_lock);
+ /* Set up the stack frame */
+ if (! (ka->sa.sa_flags & SA_NOCALLHNDLR)) {
+ if (ka->sa.sa_flags & SA_SIGINFO)
+ setup_rt_frame(sig, ka, info, oldset, regs);
+ else
+ setup_frame(sig, ka, oldset, regs);
+
+ if (!(ka->sa.sa_flags & SA_NODEFER)) {
+ spin_lock_irq(&current->sigmask_lock);
+ sigorsets(&current->blocked,&current->blocked,
+ &ka->sa.sa_mask);
+ sigaddset(&current->blocked,sig);
+ recalc_sigpending(current);
+ spin_unlock_irq(&current->sigmask_lock);
+ }
}
}

--- ./include/asm-i386/signal.h.nocallhndlr Wed Mar 27 10:56:12 2002
+++ ./include/asm-i386/signal.h Wed Mar 27 11:17:38 2002
@@ -91,6 +91,7 @@
#define SA_RESTART 0x10000000
#define SA_NODEFER 0x40000000
#define SA_RESETHAND 0x80000000
+#define SA_NOCALLHNDLR 0x00800000 /* Don't really call the handler. */

#define SA_NOMASK SA_NODEFER
#define SA_ONESHOT SA_RESETHAND

---

Attachments:

linux-nocallhndlr.patch (1.50 kB)

2002-03-27 22:00:43

by Jeff Dike

[permalink] [raw]

Subject: Re: [patch] Threads performance - allow signal handler to not call handler

---

[email protected] said:
> With this patch, if the flag is set, the signal handler won't get
> called (thus saving the overhead of going in and out of userland for
> the handler), but it will still wake up sigsuspend() and select().

I've wanted this for UML as well. I have some empty signal handlers which
exist for no reason other than to wake up pause/sigsuspend/et al.

Jeff