Messages in this thread Patch in this message | | | Date | Thu, 25 Jul 2002 20:45:12 +0530 | From | Ravikiran G Thirumalai <> | Subject | Patch 2.5.25: Ensure xtime_lock and timerlist_lock are on difft cachelines |
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I've noticed that xtime_lock and timerlist_lock ends up on the same cacheline all the time (atleaset on x86). Not a good thing for loads with high xxx_timer and do_gettimeofday counts I guess (networking etc).
Here's a 2.5.25 objdump:
c0302780 g O .data 00000004 time_freq c0302784 g O .data 00000004 timerlist_lock c0302788 g O .data 00000004 tqueue_lock c030278c g O .data 00000004 xtime_lock c0302790 l O .data 00000004 count.3 c0302794 l O .data 00000004 uidhash_lock c0302798 g O .data 00000018 root_user
Here's a trivial 2.5.28 based fix.
-Kiran
diff -ruN -X dontdiff linux-2.5.28/kernel/timer.c align_locks/kernel/timer.c --- linux-2.5.28/kernel/timer.c Thu Jul 25 02:33:23 2002 +++ align_locks/kernel/timer.c Thu Jul 25 18:17:46 2002 @@ -169,7 +169,7 @@ } /* Initialize both explicitly - let's try to have them in the same cache line */ -spinlock_t timerlist_lock = SPIN_LOCK_UNLOCKED; +spinlock_t timerlist_lock ____cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED; #ifdef CONFIG_SMP volatile struct timer_list * volatile running_timer; @@ -327,7 +327,7 @@ spin_unlock_irq(&timerlist_lock); } -spinlock_t tqueue_lock = SPIN_LOCK_UNLOCKED; +spinlock_t tqueue_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED; void tqueue_bh(void) { @@ -633,7 +633,7 @@ * This read-write spinlock protects us from races in SMP while * playing with xtime and avenrun. */ -rwlock_t xtime_lock = RW_LOCK_UNLOCKED; +rwlock_t xtime_lock __cacheline_aligned_in_smp = RW_LOCK_UNLOCKED; unsigned long last_time_offset; static inline void update_times(void) - 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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