Performance impact of CONFIG_DEBUG? direct-io test case
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From: Dominik Brodowski on 5 Aug 2010 17:00 How large is the performance impact of CONFIG_DEBUG? Well, for the test workload I've been working with lately, dd if=<device> of=/dev/zero bs=8k count=100000 iflag=direct where <device> is a dm-crypted LVM volume consisting of several partitions on a notebook pata harddisk, I get the following results: 1) best results are ~ 28 MB/s 2) Enabling CONFIG_DEBUG_LOCK_ALLOC, which also means CONFIG_LOCKDEP being enabled, causes the transfer rate to decrease by ~ 1.2 MB/s 3) Enabling CONFIG_DEBUG_SPINLOCK && CONFIG_DEBUG_MUTEXTES or CONFIG_DEBUG_SPINLOCK_SLEEP=y costs about ~ 0.4 MB/s each 4) Enabling all of the following options: CONFIG_DEBUG_RT_MUTEXES CONFIG_DEBUG_PI_LIST CONFIG_PROVE_LOCKING CONFIG_LOCK_STAT CONFIG_DEBUG_LOCKDEP costs another ~ 5 MB/s. So, for this test case, the performance impact of (some) CONFIG_DEBUG options is highly significant, here by about 25 %. Best, Dominik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |