4K stacks for everyone?
Posted Sep 8, 2005 7:02 UTC (Thu) by jwb
Parent article: 4K stacks for everyone?
A friend relayed this excellent suggestion. Instead of causing great pain among users of ndiswrapper, raid, cryptoloop, xfs, nfs, lustre, and a great many other kernel features, why not accelerate the move to 16KiB soft pages on x86? Then the stack could be kept in a single softpage, with the last 4KiB hardware backing page unallocated. That leaves 12KiB in the stack, and a reliable means of determining when the stack overflows. In addition you get all the other efficiency benefits of larger pages.
The current proposal is sheer madness. The developers have NO IDEA what the maximum kernel stack usage is, and no way of determining it. They who are proposing mandatory 4KiB stacks are just crossing their fingers and saying "fuckit, it seems to run on my laptop." That's not a very modern method of software development, especially when the only beneficiaries are a couple of large [elided] customers with over-threaded Java apps.
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