From b01288d509b0f9e45f23ae48f2366f85f489089c Mon Sep 17 00:00:00 2001 From: Ben Gamari Date: Fri, 22 Jan 2016 16:22:13 +0100 Subject: rts: Disable tick timer unless really needed Trac #9105 notes significant CPU usage by an otherwise idle process when compiled with profiling. The reason for this is that we keep the tick timer active in the profiling RTS even if profiling wasn't requested at runtime. If the user requests any sort of profiling then we need to keep the timer active to ensure that samples are collected. Test Plan: Validate, check CPU usage, ensure profiling still works Reviewers: simonmar, austin Reviewed By: simonmar, austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1822 GHC Trac Issues: #9105 --- rts/Timer.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'rts/Timer.c') diff --git a/rts/Timer.c b/rts/Timer.c index 99c09b03a3..bf7240b96a 100644 --- a/rts/Timer.c +++ b/rts/Timer.c @@ -72,10 +72,15 @@ handle_tick(int unused STG_UNUSED) #endif } else { recent_activity = ACTIVITY_DONE_GC; - // disable timer signals (see #1623, #5991) - // but only if we're not profiling + // disable timer signals (see #1623, #5991, #9105) + // but only if we're not profiling (e.g. passed -h or -p RTS + // flags). If we are profiling we need to keep the timer active + // so that samples continue to be collected. #ifndef PROFILING - stopTimer(); + if (!(RtsFlags.ProfFlags.doHeapProfile + || RtsFlags.CcFlags.doCostCentres)) { + stopTimer(); + } #endif } } else { -- cgit v1.2.1