Date: Fri, 2 Jan 2015 18:15:06 -0500 From: grarpamp <grarpamp@gmail.com> To: freebsd-performance@freebsd.org Cc: tor-dev@lists.torproject.org Subject: Re: Fwd: [tor-dev] gettimeofday() Syscall Issues Message-ID: <CAD2Ti2-8QPK-T_6LRdGRUiFC4YN5o0MzcqU7HhsUoNEuU5O7LQ@mail.gmail.com> In-Reply-To: <20150102172447.GT42409@kib.kiev.ua> References: <54A43EC4.2030706@mykolab.com> <smuiogrwo2w.fsf@linuxpal.mit.edu> <9BF461F5-D6B6-4287-BE8B-87B281FE93D0@gmail.com> <20150101033733.4b295d3b@schwanenlied.me> <CAKDKvuwMyHktLnhcuz-jCOoZc58yinzraq17bbOMkwCFbFADhg@mail.gmail.com> <54A621C2.2060408@mykolab.com> <20150102102036.0a52b072@schwanenlied.me> <CAD2Ti28ThH5shL3q5295Ck9SNBvJa46W6XcbbY%2BZ81YJTWeKtw@mail.gmail.com> <20150102172447.GT42409@kib.kiev.ua>
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On Fri, Jan 2, 2015 at 12:24 PM, Konstantin Belousov <kostikbel@gmail.com> wrote: > On Fri, Jan 02, 2015 at 09:09:34AM -0500, grarpamp wrote: >> Some recent FreeBSD related questions in this app area. >> > What is the question ? > > As a background, I can repeat that FreeBSD implements syscall-less > gettimeofday() and clock_gettime() for x86 machines which have > usable RDTSC. The selection of the timecounter can be verified > by sysctl kern.timecounter.hardware, and enabled by default fast > gettimeofday(2) can be checked by sysctl kern.timecounter.fast_gettime. > > On some Nehalem machine, I see it doing ~30M calls/sec with enabled > fast_gettime, and ~6.25M calls/sec with disabled fast_gettime. This is > measured on 2.8GHz Core i7 930 with src/tools/tools/syscall_timing. > > Check your timecounter hardware. Since it was noted that the tests > were done in VM, check the quality of RDTSC emulation in your hypervisor. https://lists.torproject.org/pipermail/tor-dev/2015-January/thread.html http://docs.freebsd.org/mail/current/freebsd-performance.html Maybe I can just refer non subscribers out to the two lists above that way in case anyone sees anything interesting they can join/comment as desired. Background might be that Tor operators have some large relays on *BSD and were looking to validate, and ways to improve, performance there. Cheers. https://lists.torproject.org/pipermail/tor-relays/ https://lists.torproject.org/pipermail/tor-talk/
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