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 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
