mprotect and vmas
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From: Ulrich Drepper on 14 Apr 2010 21:00 Quite some time there was a discussion around mprotect and why it creates vmas. The issue never got resolved IIRC but the urgency is more pressing than ever. We have today commodity machines with 8 sockets and 512G of RAM with single processes using all these resources. From what I remember the idea was that an mprotect call shouldn't really have to split a vma. Frequent examples are DSO loading, the malloc implementation, or thread stacks. They both have to change the protection of a memory region to PROT_NONE or in other cases add/remove PROT_WRITE etc. This information could be represented in the page table tree alone and doesn't require a vma split. Is this something that can be considered? This could reduce the number of vmas in a large process significantly, reducing the cost of finding a specific vma or, perhaps more importantly, gaps. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |