On Sun, 25 May 2008, Arjan van de Ven wrote: > On Sat, 24 May 2008 23:11:20 -0400 (EDT) > Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > > > In git commit 35d5d08a085c56f153458c3f5d8ce24123617faf, Andrew Morton > > placed preempt_disable around the entire delay due to TSC's not > > working nicely on SMP. Unfortunately for those that care about > > latencies this is devastating! Especially when we have callers to > > mdelay(8). > > we used to have a WARN_ON if mdelay was called while preemptable.. > maybe we should put that back in? > That would be a good idea, but that wouldn't solve this issue. The issue here is that the mdelay itself disables preemption. The caller had preemption enabled. The problem was caused by a quick fix by Andrew to handle out of sync TSC's for a delay that used TSC's as a counter. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
