Date: Fri, 9 Sep 2011 22:06:01 +1000 From: Peter Jeremy <peterjeremy@acm.org> To: Manish Vachharajani <manishv@lineratesystems.com> Cc: freebsd-hackers@freebsd.org Subject: Re: excessive use of gettimeofday(2) and other syscalls Message-ID: <20110909120601.GA40207@server.vk2pj.dyndns.org> In-Reply-To: <CAHRgBhSxiN=KBvN=Ve5cmXY_PtCuivQY1jC87O-D7QRE9qiOqA@mail.gmail.com> References: <20110906220115.GA25048@freebsd.org> <CAHRgBhRe8n%2BV3nSzRn4_fctHB1nie2ACk7oRVOPJqqKaMUgKrg@mail.gmail.com> <CAF6rxg=kzHP4zr_=LGnJDUQu-xEwgpy6QN=Lk4jqXa6hs=epKg@mail.gmail.com> <CAHRgBhT%2BKi%2BYPiK%2Bhn=fJ91eA=31tOaTPe_5xLSHQawa=%2BFD0Q@mail.gmail.com> <CAHwLALMwOu8wc5W03dar5fhkWkjN6f7eDGAT4a1u%2BK4eHHSsng@mail.gmail.com> <20110907061741.GC96277@server.vk2pj.dyndns.org> <CAHRgBhSxiN=KBvN=Ve5cmXY_PtCuivQY1jC87O-D7QRE9qiOqA@mail.gmail.com>
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--FL5UXtIhxfXey3p5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2011-Sep-07 12:41:54 -0600, Manish Vachharajani <manishv@lineratesystems= =2Ecom> wrote: >This is great info, thanks. Is it worth having some kind of >environment variable tunable (or even compile time tunable) to have a >"fast" gettimeofday then? Maybe. rwatson@ produced a preloadable .so to do this - see http://www.watson.org/~robert/freebsd/clock/ > Is there a complimentary body of code that >assumes gettimeofday is precise? I'm not aware of any but it's not necessarily trivial to identify such code - it's unlikely to fail outright but instead may deliver results that may not be as accurate as the author intended. I think a better way of looking at the problem is that some code was designed on the assumption that certain operations were cheap and therefore uses those operations more freely than it would have had those operations been more expensive. --=20 Peter Jeremy --FL5UXtIhxfXey3p5 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAk5qASkACgkQ/opHv/APuIdg7wCePFYfNxkvqHlFoKgEE2PctPCI M/YAoKCLIvPpSPXM5GgitK11RmiC/8SH =mjFy -----END PGP SIGNATURE----- --FL5UXtIhxfXey3p5--
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