From d53d04473e0d6ca1765f1117072eec59187a7f7b Mon Sep 17 00:00:00 2001 From: Andreas Hansson Date: Tue, 28 Aug 2012 14:30:31 -0400 Subject: Clock: Rework clocks to avoid tick-to-cycle transformations This patch introduces the notion of a clock update function that aims to avoid costly divisions when turning the current tick into a cycle. Each clocked object advances a private (hidden) cycle member and a tick member and uses these to implement functions for getting the tick of the next cycle, or the tick of a cycle some time in the future. In the different modules using the clocks, changes are made to avoid counting in ticks only to later translate to cycles. There are a few oddities in how the O3 and inorder CPU count idle cycles, as seen by a few locations where a cycle is subtracted in the calculation. This is done such that the regression does not change any stats, but should be revisited in a future patch. Another, much needed, change that is not done as part of this patch is to introduce a new typedef uint64_t Cycle to be able to at least hint at the unit of the variables counting Ticks vs Cycles. This will be done as a follow-up patch. As an additional follow up, the thread context still uses ticks for the book keeping of last activate and last suspend and this should probably also be changed into cycles as well. --- src/arch/arm/table_walker.cc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/arch/arm') diff --git a/src/arch/arm/table_walker.cc b/src/arch/arm/table_walker.cc index ea71e6f1c..ffa193fbe 100644 --- a/src/arch/arm/table_walker.cc +++ b/src/arch/arm/table_walker.cc @@ -758,7 +758,7 @@ void TableWalker::nextWalk(ThreadContext *tc) { if (pendingQueue.size()) - schedule(doProcessEvent, tc->getCpuPtr()->nextCycle(curTick()+1)); + schedule(doProcessEvent, tc->getCpuPtr()->clockEdge(1)); } -- cgit v1.2.3