Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] Prevent spinlock debug from timing out too early | Date | Mon, 6 Feb 2006 22:16:28 +0100 |
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In modern Linux loops_per_jiffie doesn't have much relationship to how fast the CPU can really execute loops because delay works in a different way. Unfortunately the spinlock debugging code used it for that, which caused it it time timeout much earlier that a second.
A second is quite a long time for a spinlock, but there are situations that can hold them quite long (debug output over slow serial line, SCSI driver in recovery etc.), so it's better to not time out too early.
This patch changes it to use jiffies to check for the timeout. It has the small drawback over the previous case that if jiffies doesn't tick anymore you won't get any timed out spinlocks, but normally NMI watchdog should catch that anyways.
Signed-off-by: Andi Kleen <ak@suse.de>
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(); } /* lockup suspected: */ if (print_once) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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