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/dev/ns_gige.cc | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src/dev/ns_gige.cc') diff --git a/src/dev/ns_gige.cc b/src/dev/ns_gige.cc index 6a55516c5..583cdb140 100644 --- a/src/dev/ns_gige.cc +++ b/src/dev/ns_gige.cc @@ -1147,7 +1147,7 @@ NSGigE::rxKick() } // Go to the next state machine clock tick. - rxKickTick = curTick() + ticks(1); + rxKickTick = curTick() + clockPeriod(); } switch(rxDmaState) { @@ -1594,7 +1594,7 @@ NSGigE::txKick() } // Go to the next state machine clock tick. - txKickTick = curTick() + ticks(1); + txKickTick = curTick() + clockPeriod(); } switch(txDmaState) { @@ -2015,7 +2015,7 @@ NSGigE::transferDone() DPRINTF(Ethernet, "transfer complete: data in txFifo...schedule xmit\n"); - reschedule(txEvent, curTick() + ticks(1), true); + reschedule(txEvent, curTick() + clockPeriod(), true); } bool -- cgit v1.2.3