Messages in this thread |  | | From | (Eric W. Biederman) | Subject | Re: [RFC][PATCH 6/6] automatic tuning applied to some kernel components | Date | Wed, 07 Feb 2007 14:18:57 -0700 |
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Nadia Derbey <Nadia.Derbey@bull.net> writes:
> > 2) why autotuning: > There are at least 3 cases where it can be useful > . for workloads that are known to need a big amount of a given resource type > (say shared memories), but we don't know what the maximum amount needed will be > . to solve the case of multiple applications running on a single system, and > that need the same tunable to be adjusted to feet their needs > . to make a system correctly react to eventual peak loads for a given resource > usage, i.e. make it tune up *and down* as needed.
> > In all these cases, the akt framework will enable the kernel to adapt to > increasing / decreasing resource consumption: > 1) avoid allocating "a priori" a big amount of memory that will be used only in > extreme cases. This is the effect of doing an "echo <huge_value> >> /proc/sys/kernel/shmmni" > > 2) the system will come back to the default values as soon as the peak load is > over.
At least the ipc ones are supposed to be DOS limits not behavior modifiers. I do admit from looking at the code that there are some consequences of increasing things like shmmni. However I think we would be better off with better data structures and implementations that remove these consequences than this autotuning of denial-of-service limits.
i.e. I think you are treating the symptom not the problem.
Does this make sense?
Eric
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