Hello Mikulas, On 04/19/12 12:03, Mikulas Patocka wrote: > http://people.redhat.com/mpatocka/patches/kernel/dm-lock-optimization/ > > The patches remove cache-line bouncing from device mapper when multiple > processors submit requests simultaneously. I think the idea of optimization is nice. >From a quick look, however, I have some comments: dm-optimize-no-irqsave-map-lock.patch: - dm_get_live_table() is called from request_fn, that can be called from in_interrupt context. So the added BUG_ON will be triggered. dm-optimize-percpu-io-lock.patch: - The following existing mechanisms could be used: * include/linux/rcupdate.h * include/linux/lglock.h (or extended if necessary). dm-optimize-get_live_table_fast.patch: - dm_lld_busy() can (theoretically, if dm-mpath is stacked) be called from in_interrupt context and trigger the BUG_ON. -- Jun'ichi Nomura, NEC Corporation -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
