Re: [PATCH 24/29] ia64/pv_ops/xen: implement xen pv_time_ops.

[Jeremy Fitzhardinge <jeremy@goop.org>]

Isaku Yamahata wrote:
> implement xen pv_time_ops to account steal time.
>   

I think you could just share arch/x86/xen/time.c, couldn't you?  I'd be 
happy to accept a patch to move all the shareable bits into 
drivers/xen/time.c.

    J

> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
> Signed-off-by: Alex Williamson <alex.williamson@hp.com>
> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
> ---
>  arch/ia64/xen/Makefile     |    2 +-
>  arch/ia64/xen/time.c       |  165 ++++++++++++++++++++++++++++++++++++++++++++
>  arch/ia64/xen/time.h       |   23 ++++++
>  arch/ia64/xen/xen_pv_ops.c |    2 +
>  4 files changed, 191 insertions(+), 1 deletions(-)
>  create mode 100644 arch/ia64/xen/time.c
>  create mode 100644 arch/ia64/xen/time.h
>
> diff --git a/arch/ia64/xen/Makefile b/arch/ia64/xen/Makefile
> index 01c4289..ed31c76 100644
> --- a/arch/ia64/xen/Makefile
> +++ b/arch/ia64/xen/Makefile
> @@ -3,7 +3,7 @@
>  #
>  
>  obj-y := hypercall.o xenivt.o xensetup.o xen_pv_ops.o irq_xen.o \
> -	 hypervisor.o xencomm.o xcom_hcall.o grant-table.o
> +	 hypervisor.o xencomm.o xcom_hcall.o grant-table.o time.o
>  
>  AFLAGS_xenivt.o += -D__IA64_ASM_PARAVIRTUALIZED_XEN
>  
> diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c
> new file mode 100644
> index 0000000..3414f1e
> --- /dev/null
> +++ b/arch/ia64/xen/time.c
> @@ -0,0 +1,165 @@
> +/******************************************************************************
> + * arch/ia64/xen/time.c
> + *
> + * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
> + *                    VA Linux Systems Japan K.K.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + *
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/kernel_stat.h>
> +#include <linux/posix-timers.h>
> +#include <linux/irq.h>
> +#include <linux/clocksource.h>
> +
> +#include <asm/xen/hypervisor.h>
> +
> +#include <xen/interface/vcpu.h>
> +
> +#include "../kernel/fsyscall_gtod_data.h"
> +
> +DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
> +DEFINE_PER_CPU(unsigned long, processed_stolen_time);
> +DEFINE_PER_CPU(unsigned long, processed_blocked_time);
> +
> +/* taken from i386/kernel/time-xen.c */
> +static void xen_init_missing_ticks_accounting(int cpu)
> +{
> +	struct vcpu_register_runstate_memory_area area;
> +	struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
> +	int rc;
> +
> +	memset(runstate, 0, sizeof(*runstate));
> +
> +	area.addr.v = runstate;
> +	rc = HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu,
> +				&area);
> +	WARN_ON(rc && rc != -ENOSYS);
> +
> +	per_cpu(processed_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
> +	per_cpu(processed_stolen_time, cpu) = runstate->time[RUNSTATE_runnable]
> +					    + runstate->time[RUNSTATE_offline];
> +}
> +
> +#define NS_PER_TICK (1000000000LL/HZ)
> +
> +static unsigned long
> +consider_steal_time(unsigned long new_itm)
> +{
> +	unsigned long stolen, blocked, sched_time;
> +	unsigned long delta_itm = 0, stolentick = 0;
> +	int cpu = smp_processor_id();
> +	struct vcpu_runstate_info *runstate;
> +	struct task_struct *p = current;
> +
> +	runstate = &per_cpu(runstate, smp_processor_id());
> +
> +	do {
> +		sched_time = runstate->state_entry_time;
> +		mb();
> +		stolen = runstate->time[RUNSTATE_runnable] +
> +			 runstate->time[RUNSTATE_offline] -
> +			 per_cpu(processed_stolen_time, cpu);
> +		blocked = runstate->time[RUNSTATE_blocked] -
> +			  per_cpu(processed_blocked_time, cpu);
> +		mb();
> +	} while (sched_time != runstate->state_entry_time);
> +
> +	/*
> +	 * Check for vcpu migration effect
> +	 * In this case, itc value is reversed.
> +	 * This causes huge stolen value.
> +	 * This function just checks and reject this effect.
> +	 */
> +	if (!time_after_eq(runstate->time[RUNSTATE_blocked],
> +			   per_cpu(processed_blocked_time, cpu)))
> +		blocked = 0;
> +
> +	if (!time_after_eq(runstate->time[RUNSTATE_runnable] +
> +			   runstate->time[RUNSTATE_offline],
> +			   per_cpu(processed_stolen_time, cpu)))
> +		stolen = 0;
> +
> +	if (!time_after(delta_itm + new_itm, ia64_get_itc()))
> +		stolentick = ia64_get_itc() - new_itm;
> +
> +	do_div(stolentick, NS_PER_TICK);
> +	stolentick++;
> +
> +	do_div(stolen, NS_PER_TICK);
> +
> +	if (stolen > stolentick)
> +		stolen = stolentick;
> +
> +	stolentick -= stolen;
> +	do_div(blocked, NS_PER_TICK);
> +
> +	if (blocked > stolentick)
> +		blocked = stolentick;
> +
> +	if (stolen > 0 || blocked > 0) {
> +		account_steal_time(NULL, jiffies_to_cputime(stolen));
> +		account_steal_time(idle_task(cpu), jiffies_to_cputime(blocked));
> +		run_local_timers();
> +
> +		if (rcu_pending(cpu))
> +			rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
> +
> +		scheduler_tick();
> +		run_posix_cpu_timers(p);
> +		delta_itm += local_cpu_data->itm_delta * (stolen + blocked);
> +
> +		if (cpu = time_keeper_id) {
> +			write_seqlock(&xtime_lock);
> +			do_timer(stolen + blocked);
> +			local_cpu_data->itm_next = delta_itm + new_itm;
> +			write_sequnlock(&xtime_lock);
> +		} else {
> +			local_cpu_data->itm_next = delta_itm + new_itm;
> +		}
> +		per_cpu(processed_stolen_time, cpu) += NS_PER_TICK * stolen;
> +		per_cpu(processed_blocked_time, cpu) += NS_PER_TICK * blocked;
> +	}
> +	return delta_itm;
> +}
> +
> +static int xen_do_steal_accounting(unsigned long *new_itm)
> +{
> +	unsigned long delta_itm;
> +	delta_itm = consider_steal_time(*new_itm);
> +	*new_itm += delta_itm;
> +	if (time_after(*new_itm, ia64_get_itc()) && delta_itm)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +static void xen_itc_jitter_data_reset(void)
> +{
> +	u64 lcycle, ret;
> +
> +	do {
> +		lcycle = itc_jitter_data.itc_lastcycle;
> +		ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, 0);
> +	} while (unlikely(ret != lcycle));
> +}
> +
> +struct pv_time_ops xen_time_ops __initdata = {
> +	.init_missing_ticks_accounting	= xen_init_missing_ticks_accounting,
> +	.do_steal_accounting		= xen_do_steal_accounting,
> +	.clocksource_resume		= xen_itc_jitter_data_reset,
> +};
> diff --git a/arch/ia64/xen/time.h b/arch/ia64/xen/time.h
> new file mode 100644
> index 0000000..b9c7ec5
> --- /dev/null
> +++ b/arch/ia64/xen/time.h
> @@ -0,0 +1,23 @@
> +/******************************************************************************
> + * arch/ia64/xen/time.h
> + *
> + * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
> + *                    VA Linux Systems Japan K.K.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + *
> + */
> +
> +extern struct pv_time_ops xen_time_ops __initdata;
> diff --git a/arch/ia64/xen/xen_pv_ops.c b/arch/ia64/xen/xen_pv_ops.c
> index 0ac166c..5f83036 100644
> --- a/arch/ia64/xen/xen_pv_ops.c
> +++ b/arch/ia64/xen/xen_pv_ops.c
> @@ -30,6 +30,7 @@
>  #include <asm/xen/privop.h>
>  
>  #include "irq_xen.h"
> +#include "time.h"
>  
>  /***************************************************************************
>   * general info
> @@ -357,6 +358,7 @@ xen_setup_pv_ops(void)
>  	pv_cpu_ops = xen_cpu_ops;
>  	pv_iosapic_ops = xen_iosapic_ops;
>  	pv_irq_ops = xen_irq_ops;
> +	pv_time_ops = xen_time_ops;
>  
>  	paravirt_cpu_asm_init(&xen_cpu_asm_switch);
>  }
>