Messages in this thread | | | Date | Tue, 20 Apr 2010 18:32:52 +0100 | From | Alan Cox <> | Subject | Re: Should calculation of vm.overcommit_ratio be changed? |
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> might have 4GB RAM and 1GB swap. I don't think you would expect > Desktop users to understand or tweak overcommit_ratio, but I also > don't think having the distro simply change the default from 50 (to > 100 or something else) would cover all the cases well.
Sounds like the distribution should be tuning the value according to the > > Would it make more sense to have the overcommit formula be calculated as: > > max commit = min(swap, ram) * overcommit_ratio + max(swap, ram) ? > > When swap>=ram, the formula works exactly the same as it does now, but > when ram>>swap, you are guaranteed to always be able to your full RAM > (even when swap=0).
Which is wromg - some of your RAM ends up eaten by the kernel, by pagetables and buffers etc. 50% is probably very conservative but the point of VM overcommit is exactly that - and you end up deploying swap as a precaution against disaster rather than because you need it.
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