Messages in this thread | | | From | <> | Subject | RE: [PATCH 0/5] Some vmevent fixes... | Date | Tue, 5 Jun 2012 08:16:12 +0000 |
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> -----Original Message----- > From: penberg@gmail.com [mailto:penberg@gmail.com] On Behalf Of ext > Pekka Enberg > Sent: 05 June, 2012 11:02 > To: Minchan Kim ... > > Next concern is that periodic timer of implementation. > > I think it would add direct hook in vmscan.c rather than peeking raw > > vmstat periodically by timer so we can control more fine-grained way > without unnecessary overhead. > > If the hooks are clean and it doesn't hurt the !CONFIG_VMEVENT case, I'm > completely OK with that.
On the previous iteration hooking vm was pointed as very bad idea, so in my version I installed shrinker to handle cases when we have memory pressure. Using deferred timer with adequate timeout (0.250 ms or larger) fully suitable for userspace and produce adequate overhead -> by nature such API should not be 100% accurate, anyhow applications cannot handle situation as good as kernel can provide, 0.5MB space accuracy, 100ms is maximum user-space require for 64-1024MB devices.
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