Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751556AbWH3GNW (ORCPT ); Wed, 30 Aug 2006 02:13:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751553AbWH3GNW (ORCPT ); Wed, 30 Aug 2006 02:13:22 -0400 Received: from ozlabs.tip.net.au ([203.10.76.45]:62162 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S1751548AbWH3GNV (ORCPT ); Wed, 30 Aug 2006 02:13:21 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17653.11388.637189.113422@cargo.ozlabs.ibm.com> Date: Wed, 30 Aug 2006 16:13:16 +1000 From: Paul Mackerras To: Olaf Hering Cc: Nathan Lynch , Linus Torvalds , Linux Kernel Mailing List , linuxppc-dev@ozlabs.org Subject: Re: Linux v2.6.18-rc5 In-Reply-To: <20060829155216.GA25861@aepfle.de> References: <20060829115537.GA24256@aepfle.de> <20060829130629.GW11309@localdomain> <20060829155216.GA25861@aepfle.de> X-Mailer: VM 7.19 under Emacs 21.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4400 Lines: 119 Olaf, This patch should fix it. The problem was that I was comparing a 32-bit quantity with a 64-bit quantity, and consequently time wasn't advancing. This makes us use a 64-bit quantity on all platforms, which ends up simplifying the code since we can now get rid of the tb_last_stamp variable (which actually fixes another bug that Ben H and I noticed while going carefully through the code). This works fine on my G4 tibook. Let me know how it goes on your machines. Paul. diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 18e59e4..a124499 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -125,15 +125,8 @@ static long timezone_offset; unsigned long ppc_proc_freq; unsigned long ppc_tb_freq; -u64 tb_last_jiffy __cacheline_aligned_in_smp; -unsigned long tb_last_stamp; - -/* - * Note that on ppc32 this only stores the bottom 32 bits of - * the timebase value, but that's enough to tell when a jiffy - * has passed. - */ -DEFINE_PER_CPU(unsigned long, last_jiffy); +static u64 tb_last_jiffy __cacheline_aligned_in_smp; +static DEFINE_PER_CPU(u64, last_jiffy); #ifdef CONFIG_VIRT_CPU_ACCOUNTING /* @@ -458,7 +451,7 @@ void do_gettimeofday(struct timeval *tv) do { seq = read_seqbegin_irqsave(&xtime_lock, flags); sec = xtime.tv_sec; - nsec = xtime.tv_nsec + tb_ticks_since(tb_last_stamp); + nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy); } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); usec = nsec / 1000; while (usec >= 1000000) { @@ -700,7 +693,6 @@ #endif tb_next_jiffy = tb_last_jiffy + tb_ticks_per_jiffy; if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) { tb_last_jiffy = tb_next_jiffy; - tb_last_stamp = per_cpu(last_jiffy, cpu); do_timer(regs); timer_recalc_offset(tb_last_jiffy); timer_check_rtc(); @@ -749,7 +741,7 @@ void __init smp_space_timers(unsigned in int i; unsigned long half = tb_ticks_per_jiffy / 2; unsigned long offset = tb_ticks_per_jiffy / max_cpus; - unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid); + u64 previous_tb = per_cpu(last_jiffy, boot_cpuid); /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */ previous_tb -= tb_ticks_per_jiffy; @@ -830,7 +822,7 @@ #endif * and therefore the (jiffies - wall_jiffies) computation * has been removed. */ - tb_delta = tb_ticks_since(tb_last_stamp); + tb_delta = tb_ticks_since(tb_last_jiffy); tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */ new_nsec -= SCALE_XSEC(tb_delta, 1000000000); @@ -950,8 +942,7 @@ void __init time_init(void) if (__USE_RTC()) { /* 601 processor: dec counts down by 128 every 128ns */ ppc_tb_freq = 1000000000; - tb_last_stamp = get_rtcl(); - tb_last_jiffy = tb_last_stamp; + tb_last_jiffy = get_rtcl(); } else { /* Normal PowerPC with timebase register */ ppc_md.calibrate_decr(); @@ -959,7 +950,7 @@ void __init time_init(void) ppc_tb_freq / 1000000, ppc_tb_freq % 1000000); printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n", ppc_proc_freq / 1000000, ppc_proc_freq % 1000000); - tb_last_stamp = tb_last_jiffy = get_tb(); + tb_last_jiffy = get_tb(); } tb_ticks_per_jiffy = ppc_tb_freq / HZ; @@ -1036,7 +1027,7 @@ void __init time_init(void) do_gtod.varp = &do_gtod.vars[0]; do_gtod.var_idx = 0; do_gtod.varp->tb_orig_stamp = tb_last_jiffy; - __get_cpu_var(last_jiffy) = tb_last_stamp; + __get_cpu_var(last_jiffy) = tb_last_jiffy; do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC; do_gtod.tb_ticks_per_sec = tb_ticks_per_sec; do_gtod.varp->tb_to_xs = tb_to_xs; diff --git a/include/asm-powerpc/time.h b/include/asm-powerpc/time.h index dcde441..5785ac4 100644 --- a/include/asm-powerpc/time.h +++ b/include/asm-powerpc/time.h @@ -30,10 +30,6 @@ extern unsigned long tb_ticks_per_usec; extern unsigned long tb_ticks_per_sec; extern u64 tb_to_xs; extern unsigned tb_to_us; -extern unsigned long tb_last_stamp; -extern u64 tb_last_jiffy; - -DECLARE_PER_CPU(unsigned long, last_jiffy); struct rtc_time; extern void to_tm(int tim, struct rtc_time * tm); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/