linux-kernel - Re: [PATCH 2/10] x86: convert to generic helpers for IPI function calls

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Message-ID: <483E9D9B.9030202@goop.org>
Date:	Thu, 29 May 2008 13:12:11 +0100
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Jens Axboe <jens.axboe@...cle.com>
CC:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	npiggin@...e.de, linux-arch@...r.kernel.org, mingo@...e.hu,
	paulmck@...ux.vnet.ibm.com
Subject: Re: [PATCH 2/10] x86: convert to generic helpers for IPI function
 calls

Jens Axboe wrote:
> @@ -122,6 +109,17 @@ static int xen_smp_intr_init(unsigned int cpu)
>  		goto fail;
>  	per_cpu(debug_irq, cpu) = rc;
>  
> +	callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
> +	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
> +				    cpu,
> +				    xen_call_function_single_interrupt,
> +				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
> +				    callfunc_name,
> +				    NULL);
> +	if (rc < 0)
> +		goto fail;
> +	per_cpu(callfuncsingle_irq, cpu) = rc;
>   

Tiny nit: could you shift this up below the other callfunc registration, 
so they appear next to each other in /proc?

> +void xen_smp_send_call_function_ipi(cpumask_t mask)
> +{
> +	int cpu;
> +
> +	xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
> +
> +	/* Make sure other vcpus get a chance to run if they need to. */
> +	for_each_cpu_mask(cpu, mask) {
> +		if (xen_vcpu_stolen(cpu)) {
> +			HYPERVISOR_sched_op(SCHEDOP_yield, 0);
> +			break;
> +		}
> +	}
>   

I think you should just drop this loop for now; I want to do some 
measurements before putting it in.

Thanks,
    J
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