Messages in this thread |  | | From | Jesse Barnes <> | | Subject | Re: [PATCH] shows Active/Inactive on per-node meminfo | | Date | Fri, 20 Aug 2004 15:01:31 -0400 |
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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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