Messages in this thread | | | From | Linus Torvalds <> | Date | Sat, 1 Sep 2018 14:38:43 -0700 | Subject | Re: Redoing eXclusive Page Frame Ownership (XPFO) with isolated CPUs in mind (for KVM to isolate its guests per CPU) |
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On Fri, Aug 31, 2018 at 12:45 AM Julian Stecklina <jsteckli@amazon.de> wrote: > > I've been spending some cycles on the XPFO patch set this week. For the > patch set as it was posted for v4.13, the performance overhead of > compiling a Linux kernel is ~40% on x86_64[1]. The overhead comes almost > completely from TLB flushing. If we can live with stale TLB entries > allowing temporary access (which I think is reasonable), we can remove > all TLB flushing (on x86). This reduces the overhead to 2-3% for > kernel compile.
I have to say, even 2-3% for a kernel compile sounds absolutely horrendous.
Kernel bullds are 90% user space at least for me, so a 2-3% slowdown from a kernel is not some small unnoticeable thing.
Linus
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