[Devel] Re: [RFC][PATCH] memory controller per zone patches take 2 [4/10] calculate mapped ratio for memory cgroup

[KAMEZAWA Hiroyuki]

On Thu, 22 Nov 2007 17:34:20 +0900 (JST)
yamamoto at valinux.co.jp (YAMAMOTO Takashi) wrote:

> > > > +	/* usage is recorded in bytes */
> > > > +	total = mem->res.usage >> PAGE_SHIFT;
> > > > +	rss = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_RSS);
> > > > +	return (rss * 100) / total;
> > > 
> > > Never tried 64 bit division on a 32 bit system. I hope we don't
> > > have to resort to do_div() sort of functionality.
> > > 
> > Hmm, maybe it's better to make these numebrs be just "long".
> > I'll try to change per-cpu-counter implementation.
> > 
> > Thanks,
> > -Kame
> 
> besides that, i think 'total' can be zero here.
> 
Ah, This is what I do now.
==
+/*
+ * Calculate mapped_ratio under memory controller. This will be used in
+ * vmscan.c for deteremining we have to reclaim mapped pages.
+ */
+int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem)
+{
+       long total, rss;
+
+       /*
+        * usage is recorded in bytes. But, here, we assume the number of
+        * physical pages can be represented by "long" on any arch.
+        */
+       total = (long) (mem->res.usage >> PAGE_SHIFT);
+       rss = (long)mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_RSS);
+       return (int)((rss * 100L) / total);
+}
==

maybe works well.

-Kame

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