3 ms·
Or you could have separate virtual address spaces for kernel / userland.
by armitron 11y ago
Or you could have separate virtual address spaces for kernel / userland.
- Dylan16807 11y agoYou could, but: "Just for comparison, Linux defaults to 3 GB for user mode and 1 GB for kernel mode. There are experimental patches to implement a separate virtual address space for the kernel, thus granting 4 GB for user mode AND 4 GB for kernel mode. Unfortunately, there is a 10-20% performance hit because every system call requires an address space switch (and TLB cache flush)." Take it with a grain of salt, that quote is a decade old.
- lokedhs 11y agoI wonder if this is something that is limited to a 32-bit kernel. Solaris gives each process the full 4 GB in userspace, and I think that a 10-20% performance degradation compared to Linux would be noticeable.
- userbinator 11y agoIt is slower. Here's an old benchmark but presumably Linux and Solaris had the same shared vs. separate address space difference back then, and the results show it: https://pdfs.semanticscholar.org/4489/18f01d17628cb94ac69f27767f74f3d6d769.pdf https://pdfs.semanticscholar.org/4489/18f01d17628cb94ac69f27... They don't call it "Slowlaris" for nothing...