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Eric W. Biederman wrote: > Nadia Derbey <Nadia.Derbey@bull.net> writes: > > >>I do not fully agree with you: >>It is true that some ipc tunables play the role of DoS limits. >>But IMHO the *mni ones (semmni, msgmni, shmmni) are used by the ipc subsystem to >>adapt its data structures sizes to what is being asked for through the tunable >>value. I think this is how they manage to take into account a new tunable value >>without a need for rebooting the system: reallocate some more memory on demand. > > > Yes, they do. However if you are constantly having to play with shmmni or > the others that is the problem and the array should be replaced with > a hash table or some form of radix tree, so it changes it's size to fit > the need. Once that is done, shmmni does become a simple DOS limit. > > So what I'm asking is please fix the problem at the source don't plaster over > it. > > >>Now, what the akt framework does, is that it takes advantage of this concept of >>"on demand memory allocation" to replace a user (or a daemon) that would >>periodically check its ipcs consumptions and manually adjust the ipcs tunables: >>Doing this from the user space would imply a latency that makes it difficult to >>react fast enough to resources running out. > > > There may be some sense in this but you haven't found something that inherently > needs tuning. You have found something that has a poor data structure, > and can more easily be fixed by simply fixing the data structure. So, should I understand from this that automatic tuning and the AKT framework itself would make sense, given that I find the rigth tunables it should be applied to? Actually, dont' know if you had the opportunity to read all the patches, but there are 2 other tunables AKT is proposed to be applied to: . max_threads, the tunable limit on nr_threads . max_files, the tunable limit on nr_files Regards, Nadia - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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