Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754401Ab3FEXyv (ORCPT ); Wed, 5 Jun 2013 19:54:51 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:60368 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753347Ab3FEXyt (ORCPT ); Wed, 5 Jun 2013 19:54:49 -0400 From: Stephen Boyd To: John Stultz Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Russell King , arm@kernel.org, Catalin Marinas , Will Deacon , Thomas Gleixner , Christopher Covington Subject: [PATCHv3 1/3] sched_clock: Add support for >32 bit sched_clock Date: Wed, 5 Jun 2013 16:54:43 -0700 Message-Id: <1370476485-468-2-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 1.8.3.rc3.8.g5e49f30.dirty In-Reply-To: <1370476485-468-1-git-send-email-sboyd@codeaurora.org> References: <1370476485-468-1-git-send-email-sboyd@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4998 Lines: 156 The ARM architected system counter has at least 56 useable bits. Add support for counters with more than 32 bits to the generic sched_clock implementation so we can avoid the complexity of dealing with wrap-around on these devices while benefiting from the irqtime accounting and suspend/resume handling that the generic sched_clock code already has. All users should switch over to the 64bit read function so we can deprecate setup_sched_clock() in favor of sched_clock_setup(). Signed-off-by: Stephen Boyd --- I've noticed that we probably need to update the mult/shift calculation similar to how clocksources are done. Should we just copy/paste the maxsec calculation code here or do something smarter? include/linux/sched_clock.h | 1 + kernel/time/sched_clock.c | 41 +++++++++++++++++++++++++++-------------- 2 files changed, 28 insertions(+), 14 deletions(-) diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h index fa7922c..81baaef 100644 --- a/include/linux/sched_clock.h +++ b/include/linux/sched_clock.h @@ -15,6 +15,7 @@ static inline void sched_clock_postinit(void) { } #endif extern void setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate); +extern void sched_clock_setup(u64 (*read)(void), int bits, unsigned long rate); extern unsigned long long (*sched_clock_func)(void); diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index aad1ae6..3478b6d 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -14,11 +14,12 @@ #include #include #include +#include struct clock_data { u64 epoch_ns; - u32 epoch_cyc; - u32 epoch_cyc_copy; + u64 epoch_cyc; + u64 epoch_cyc_copy; unsigned long rate; u32 mult; u32 shift; @@ -35,24 +36,31 @@ static struct clock_data cd = { .mult = NSEC_PER_SEC / HZ, }; -static u32 __read_mostly sched_clock_mask = 0xffffffff; +static u64 __read_mostly sched_clock_mask; -static u32 notrace jiffy_sched_clock_read(void) +static u64 notrace jiffy_sched_clock_read(void) { - return (u32)(jiffies - INITIAL_JIFFIES); + return (u64)(jiffies - INITIAL_JIFFIES); } -static u32 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read; +static u32 __read_mostly (*read_sched_clock_32)(void); + +static u64 notrace read_sched_clock_32_wrapper(void) +{ + return read_sched_clock_32(); +} + +static u64 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read; static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift) { return (cyc * mult) >> shift; } -static unsigned long long notrace cyc_to_sched_clock(u32 cyc, u32 mask) +static unsigned long long notrace cyc_to_sched_clock(u64 cyc, u64 mask) { u64 epoch_ns; - u32 epoch_cyc; + u64 epoch_cyc; /* * Load the epoch_cyc and epoch_ns atomically. We do this by @@ -77,7 +85,7 @@ static unsigned long long notrace cyc_to_sched_clock(u32 cyc, u32 mask) static void notrace update_sched_clock(void) { unsigned long flags; - u32 cyc; + u64 cyc; u64 ns; cyc = read_sched_clock(); @@ -103,7 +111,7 @@ static void sched_clock_poll(unsigned long wrap_ticks) update_sched_clock(); } -void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) +void __init sched_clock_setup(u64 (*read)(void), int bits, unsigned long rate) { unsigned long r, w; u64 res, wrap; @@ -112,10 +120,9 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) if (cd.rate > rate) return; - BUG_ON(bits > 32); WARN_ON(!irqs_disabled()); read_sched_clock = read; - sched_clock_mask = (1 << bits) - 1; + sched_clock_mask = (1ULL << bits) - 1; cd.rate = rate; /* calculate the mult/shift to convert counter ticks to ns. */ @@ -160,9 +167,15 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) pr_debug("Registered %pF as sched_clock source\n", read); } +void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) +{ + read_sched_clock_32 = read; + sched_clock_setup(read_sched_clock_32_wrapper, bits, rate); +} + static unsigned long long notrace sched_clock_32(void) { - u32 cyc = read_sched_clock(); + u64 cyc = read_sched_clock(); return cyc_to_sched_clock(cyc, sched_clock_mask); } @@ -183,7 +196,7 @@ void __init sched_clock_postinit(void) * make it the final one one. */ if (read_sched_clock == jiffy_sched_clock_read) - setup_sched_clock(jiffy_sched_clock_read, 32, HZ); + sched_clock_setup(jiffy_sched_clock_read, BITS_PER_LONG, HZ); sched_clock_poll(sched_clock_timer.data); } -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation -- 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/