Re: [PATCH 10/17] 2.6.17.1 perfmon2 patch for review: PMU context switch

[Stephane Eranian <eranian@hpl.hp.com>]

Andi,

Thanks for your feedback. I will make the changes you
requested.

About the context switch code, what about I do the following
in __switch_to():

__kprobes struct task_struct *
__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
{
        struct thread_struct *prev = &prev_p->thread,
                                 *next = &next_p->thread;
        int cpu = smp_processor_id();
        struct tss_struct *tss = &per_cpu(init_tss, cpu);

        if (unlikely(__get_cpu_var(pmu_ctx) || next_p->pfm_context))
                __pfm_ctxswout(prev_p, next_p);

        /*
         * Reload esp0, LDT and the page table pointer:
         */
        tss->rsp0 = next->rsp0;

There is now a single hook and a conditional branch.
this is similar to what you have with the debug registers.

--
-Stephane