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SubjectRe: [PATCH] shows Active/Inactive on per-node meminfo
Date
On Friday, August 20, 2004 2:48 pm, Jesse Barnes wrote:
> On Friday, August 20, 2004 2:02 pm, mita akinobu wrote:
> > + for (i = 0; i < MAX_NR_ZONES; i++) {
> > + *active += zones[i].nr_active;
> > + *inactive += zones[i].nr_inactive;
> > + *free += zones[i].free_pages;
> > + }
> > +}
> > +
> > - *free += zone->free_pages;
> > + for_each_pgdat(pgdat) {
> > + unsigned long l, m, n;
> > + __get_zone_counts(&l, &m, &n, pgdat);
> > + *active += l;
> > + *inactive += m;
> > + *free += n;
> > }
>
> Just FYI, loops like this are going to be very slow on a large machine.
> Iterating over every node in the system involves a TLB miss on every
> iteration along with an offnode reference and possibly cacheline demotion.

...but I see that you're just adding the info to the per-node meminfo files,
so it should be ok as long as people access a node's meminfo file from a
local cpu. /proc/meminfo will still hurt a lot though.

I bring this up because I ran into it once. I created a file
called /proc/discontig which printed out detailed per-node memory stats, one
node per line. On a large system it would literally take several seconds to
cat the file due to the overhead of looking at all the pages and zone
structures.

Jesse

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