From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758646Ab0HKXuI (ORCPT ); Wed, 11 Aug 2010 19:50:08 -0400 Received: from kroah.org ([198.145.64.141]:57545 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758479Ab0HKXuC (ORCPT ); Wed, 11 Aug 2010 19:50:02 -0400 X-Mailbox-Line: From gregkh@clark.site Wed Aug 11 16:46:25 2010 Message-Id: <20100811234625.718070734@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 11 Aug 2010 16:45:48 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jeremy Fitzhardinge Subject: [09/11] xen: drop xen_sched_clock in favour of using plain wallclock time In-Reply-To: <20100811234809.GA676@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jeremy Fitzhardinge commit 8a22b9996b001c88f2bfb54c6de6a05fc39e177a upstream. xen_sched_clock only counts unstolen time. In principle this should be useful to the Linux scheduler so that it knows how much time a process actually consumed. But in practice this doesn't work very well as the scheduler expects the sched_clock time to be synchronized between cpus. It also uses sched_clock to measure the time a task spends sleeping, in which case "unstolen time" isn't meaningful. So just use plain xen_clocksource_read to return wallclock nanoseconds for sched_clock. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Greg Kroah-Hartman --- arch/x86/xen/enlighten.c | 2 +- arch/x86/xen/time.c | 43 +------------------------------------------ arch/x86/xen/xen-ops.h | 3 ++- 3 files changed, 4 insertions(+), 44 deletions(-) --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1179,7 +1179,7 @@ static const struct pv_time_ops xen_time .set_wallclock = xen_set_wallclock, .get_wallclock = xen_get_wallclock, .get_tsc_khz = xen_tsc_khz, - .sched_clock = xen_sched_clock, + .sched_clock = xen_clocksource_read, }; static const struct pv_cpu_ops xen_cpu_ops __initdata = { --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -30,8 +30,6 @@ #define TIMER_SLOP 100000 #define NS_PER_TICK (1000000000LL / HZ) -static cycle_t xen_clocksource_read(void); - /* runstate info updated by Xen */ static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate); @@ -158,45 +156,6 @@ static void do_stolen_accounting(void) account_steal_time(idle_task(smp_processor_id()), ticks); } -/* - * Xen sched_clock implementation. Returns the number of unstolen - * nanoseconds, which is nanoseconds the VCPU spent in RUNNING+BLOCKED - * states. - */ -unsigned long long xen_sched_clock(void) -{ - struct vcpu_runstate_info state; - cycle_t now; - u64 ret; - s64 offset; - - /* - * Ideally sched_clock should be called on a per-cpu basis - * anyway, so preempt should already be disabled, but that's - * not current practice at the moment. - */ - preempt_disable(); - - now = xen_clocksource_read(); - - get_runstate_snapshot(&state); - - WARN_ON(state.state != RUNSTATE_running); - - offset = now - state.state_entry_time; - if (offset < 0) - offset = 0; - - ret = state.time[RUNSTATE_blocked] + - state.time[RUNSTATE_running] + - offset; - - preempt_enable(); - - return ret; -} - - /* Get the TSC speed from Xen */ unsigned long xen_tsc_khz(void) { @@ -213,7 +172,7 @@ unsigned long xen_tsc_khz(void) return xen_khz; } -static cycle_t xen_clocksource_read(void) +cycle_t xen_clocksource_read(void) { struct pvclock_vcpu_time_info *src; cycle_t ret; --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -3,6 +3,7 @@ #include #include +#include #include /* These are code, but not functions. Defined in entry.S */ @@ -37,7 +38,7 @@ unsigned long xen_tsc_khz(void); void __init xen_time_init(void); unsigned long xen_get_wallclock(void); int xen_set_wallclock(unsigned long time); -unsigned long long xen_sched_clock(void); +cycle_t xen_clocksource_read(void); irqreturn_t xen_debug_interrupt(int irq, void *dev_id);