From patchwork Wed Jun 5 23:54:43 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Boyd X-Patchwork-Id: 2676431 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) by patchwork2.kernel.org (Postfix) with ESMTP id 3C9CCDF264 for ; Wed, 5 Jun 2013 23:56:33 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UkNYU-0002xd-7S; Wed, 05 Jun 2013 23:55:51 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UkNY8-0002Fy-TH; Wed, 05 Jun 2013 23:55:28 +0000 Received: from smtp.codeaurora.org ([198.145.11.231]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UkNXp-0002DQ-KY for linux-arm-kernel@lists.infradead.org; Wed, 05 Jun 2013 23:55:13 +0000 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id BEF3913F103; Wed, 5 Jun 2013 23:54:48 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id AE9C613F107; Wed, 5 Jun 2013 23:54:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-caf-smtp.dmz.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED autolearn=ham version=3.3.1 Received: from sboyd-linux.qualcomm.com (i-global252.qualcomm.com [199.106.103.252]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sboyd@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 0B3D713F103; Wed, 5 Jun 2013 23:54:48 +0000 (UTC) From: Stephen Boyd To: John Stultz 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> X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130605_195509_868021_0A925DA8 X-CRM114-Status: GOOD ( 20.93 ) X-Spam-Score: -2.4 (--) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-2.4 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.5 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Russell King , linux-arm-msm@vger.kernel.org, Will Deacon , linux-kernel@vger.kernel.org, arm@kernel.org, Christopher Covington , Catalin Marinas , Thomas Gleixner , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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); }