Messages in this thread |  | | | From | KOSAKI Motohiro <> | | Subject | Re: [PATCH 2/3][v2] vmstat: add anon_scan_ratio field to zoneinfo | | Date | Mon, 18 Jan 2010 11:14:52 +0900 (JST) |
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> >> It can make stale data when high memory pressure happens. > > > > ?? why? and when? > > I think it depend on what's stale mean. > > > > Currently(i.e. before the patch), get_scan_ratio have following fomula. > > in such region, recent_scanned is not protected by zone->lru_lock. > > > > ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); > > ap /= reclaim_stat->recent_rotated[0] + 1; > > fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); > > fp /= reclaim_stat->recent_rotated[1] + 1; > > percent[0] = 100 * ap / (ap + fp + 1); > > percent[1] = 100 - percent[0]; > > > > It mean, shrink_zone() doesn't use exactly recent_scanned value. then > > zoneinfo can use the same unexactly value. > > Absoultely right. I missed that. Thanks. > get_scan_ratio used lru_lock to get reclaim_stat->recent_xxxx. > But, it doesn't used lru_lock to get ap/fp. > > Is it intentional? I think you or Rik know it. :) > I think if we want to get exact value, we have to use lru_lock until > getting ap/fp. > If it isn't, we don't need lru_lock when we get the reclaim_stat->recent_xxxx. > > What do you think about it?
I believe the current code is intentional.
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