Re: [RFC][PATCH] radix-tree based page_cgroup. [7/7] per cpu fast lookup

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 25 Feb 2008 14:36:40 +0900 (JST)
yamamoto@valinux.co.jp (YAMAMOTO Takashi) wrote:

> > +
> > +static void save_result(struct page_cgroup  *base, unsigned long idx)
> > +{
> > +	int hash = idx & (PAGE_CGROUP_NR_CACHE - 1);
> > +	struct page_cgroup_cache *pcp = &__get_cpu_var(pcpu_page_cgroup_cache);
> > +	preempt_disable();
> > +	pcp->ents[hash].idx = idx;
> > +	pcp->ents[hash].base = base;
> > +	preempt_enable();
> 
> preempt_disable after __get_cpu_var doesn't make much sense.
> it should be get_cpu_var and put_cpu_var.
> 
I'm sorry that local_cpu_var doesn't take id of local cpu. 
will fix.


> > -struct page_cgroup *get_page_cgroup(struct page *page, gfp_t gfpmask);
> > +struct page_cgroup *__get_page_cgroup(struct page *page, gfp_t gfpmask);
> > +
> > +static inline struct page_cgroup *
> > +get_page_cgroup(struct page *page, gfp_t gfpmask)
> > +{
> > +	unsigned long pfn = page_to_pfn(page);
> > +	struct page_cgroup_cache *pcp = &__get_cpu_var(pcpu_page_cgroup_cache);
> > +	struct page_cgroup *ret;
> > +	unsigned long idx = pfn >> PCGRP_SHIFT;
> > +	int hnum = (idx) & (PAGE_CGROUP_NR_CACHE - 1);
> > +
> > +	preempt_disable();
> > +	if (pcp->ents[hnum].idx == idx && pcp->ents[hnum].base)
> > +		ret = pcp->ents[hnum].base + (pfn - (idx << PCGRP_SHIFT));
> > +	else
> > +		ret = NULL;
> > +	preempt_enable();
> 
> ditto.
> 

Thank you for pointing out.

Thanks,
-Kame


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