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Date:      Fri, 28 May 2010 02:00:15 +0000 (UTC)
From:      Neel Natu <neel@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r208607 - head/sys/mips/mips
Message-ID:  <201005280200.o4S20F0t050176@svn.freebsd.org>
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Author: neel
Date: Fri May 28 02:00:15 2010
New Revision: 208607
URL: http://svn.freebsd.org/changeset/base/208607

Log:
  If 'timer2hz' is zero then we don't need to call 'timer2clock()' directly. It
  will be called automatically by 'timer1clock()'.
  
  Do profiling as often as possible by running it as the same frequency as
  'timer1hz'. The statistics clock is run as close to 128Hz as possible.
  
  Pointed out by: mav@

Modified:
  head/sys/mips/mips/tick.c

Modified: head/sys/mips/mips/tick.c
==============================================================================
--- head/sys/mips/mips/tick.c	Fri May 28 01:06:40 2010	(r208606)
+++ head/sys/mips/mips/tick.c	Fri May 28 02:00:15 2010	(r208607)
@@ -127,9 +127,6 @@ void
 mips_timer_init_params(uint64_t platform_counter_freq, int double_count)
 {
 
-	stathz = hz;
-	profhz = hz;
-
 	/*
 	 * XXX: Do not use printf here: uart code 8250 may use DELAY so this
 	 * function should  be called before cninit.
@@ -143,6 +140,17 @@ mips_timer_init_params(uint64_t platform
 	if (double_count != 0)
 		counter_freq /= 2;
 
+	/*
+	 * We want to run stathz in the neighborhood of 128hz.  We would
+	 * like profhz to run as often as possible, so we let it run on
+	 * each clock tick.  We try to honor the requested 'hz' value as
+	 * much as possible.
+	 *
+	 * If 'hz' is above 1500, then we just let the timer
+	 * (and profhz) run at hz.  If 'hz' is below 1500 but above
+	 * 750, then we let the timer run at 2 * 'hz'.  If 'hz'
+	 * is below 750 then we let the timer run at 4 * 'hz'.
+	 */
 	if (hz >= 1500)
 		timer1hz = hz;
 	else if (hz >= 750)
@@ -150,6 +158,12 @@ mips_timer_init_params(uint64_t platform
 	else
 		timer1hz = hz * 4;
 
+	if (timer1hz < 128)
+		stathz = timer1hz;
+	else
+		stathz = timer1hz / (timer1hz / 128);
+	profhz = timer1hz;
+
 	cycles_per_tick = counter_freq / timer1hz;
 	cycles_per_usec = counter_freq / (1 * 1000 * 1000);
 	
@@ -285,7 +299,6 @@ clock_intr(void *arg)
 
 	while (lost_ticks >= cycles_per_tick) {
 		timer1clock(TRAPF_USERMODE(tf), tf->pc);
-		timer2clock(TRAPF_USERMODE(tf), tf->pc);
 		lost_ticks -= cycles_per_tick;
 	}
 	DPCPU_SET(lost_ticks, lost_ticks);
@@ -301,7 +314,6 @@ clock_intr(void *arg)
 		(*cyclic_clock_func[cpu])(tf);
 #endif
 	timer1clock(TRAPF_USERMODE(tf), tf->pc);
-	timer2clock(TRAPF_USERMODE(tf), tf->pc);
 	critical_exit();
 	return (FILTER_HANDLED);
 }

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