Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 14 Sep 2015 10:54:24 -0700 | Subject | Re: [PATCH v4 RESEND] x86/asm/entry/32, selftests: Add 'test_syscall_vdso' test |
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On Sep 14, 2015 1:26 AM, "Ingo Molnar" <mingo@kernel.org> wrote: > > > * Andy Lutomirski <luto@amacapital.net> wrote: > > > > (I'm not very comfortable about additional six push/pops > > > which are necessary for this to happen. I'm surprised > > > maintainers tentatively agreed to that - > > > I was grilled and asked to prove with measurements > > > that *one* additional push+pop wasn't adding significant overhead). > > > > I suspect that I need to make the series faster. > > > > Also, int $0x80 isn't a fast path for any legitimate use case except > > Debian, and I would argue that Debian is just buggy. > > So buggy in the sense of not making use of faster syscalls, right? It won't break > in any visible way, correct?
Correct. The only visible breakage I know of is that my unwind selftest fails if compiled by a Debian toolchain, and I'll fix that in v2.
> > So if this heavy int80 syscall use happens even with the latest version of Debian > as well then it would be nice to figure out what's wrong there, and provide an > optimization patch to their libc guys or so - to make sure we fully understand the > problem.
I looked for a bit and drew a blank, but I know I'm bad at understanding Debian packaging and even worse at understanding the mess that is glibc's pile of multiply compiled files. I'll file a bug or something.
--Andy
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