Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] Prevent spinlock debug from timing out too early | Date | Mon, 6 Feb 2006 22:42:30 +0100 |
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On Monday 06 February 2006 22:36, Ingo Molnar wrote: > > * Andi Kleen <ak@suse.de> wrote: > > > Index: linux-2.6.15/lib/spinlock_debug.c > > =================================================================== > > --- linux-2.6.15.orig/lib/spinlock_debug.c > > +++ linux-2.6.15/lib/spinlock_debug.c > > @@ -68,13 +68,13 @@ static inline void debug_spin_unlock(spi > > static void __spin_lock_debug(spinlock_t *lock) > > { > > int print_once = 1; > > - u64 i; > > > > for (;;) { > > - for (i = 0; i < loops_per_jiffy * HZ; i++) { > > - cpu_relax(); > > + unsigned long timeout = jiffies + HZ; > > + while (time_before(jiffies, timeout)) { > > if (__raw_spin_trylock(&lock->raw_lock)) > > return; > > + cpu_relax(); > > The reason i added a loop counter was to solve the case where we are > spinning with interrupts disabled - jiffies wont increase there!
Yes but the NMI watchdog should catch it eventually
[we really should enable it by default on i386 too - local APIC NMI should work everywhere with APIC]
Oops I missed the write lock case. Thanks.
> a better solution would be to call __delay(1) after the first failed > attempt, that would make the delay at least 1 second long. It seems > __delay() is de-facto exported by every architecture, so we can rely on > it in the global spinlock code. > > So how about the patch below instead?
Are you sure loops_per_jiffie is always in delay(1) units?
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