Date: Mon, 6 Oct 2008 23:57:49 +0200 From: Roland Smith <rsmith@xs4all.nl> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Cc: freebsd-questions@freebsd.org Subject: Re: TRUE realtime priority Message-ID: <20081006215749.GA68933@slackbox.xs4all.nl> In-Reply-To: <20081006221523.P3921@wojtek.tensor.gdynia.pl> References: <20081006221523.P3921@wojtek.tensor.gdynia.pl>
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--82I3+IH0IqGh5yIs Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 06, 2008 at 10:21:01PM +0200, Wojciech Puchar wrote: > is it possible on FreeBSD No, I think. =20 > i run asterisk with realtime priority. it works perfectly no matter how= =20 > much CPU is loaded by other non-telephony tasks. >=20 > but with lots of VM pressure it starts to so... like like tha..that... >=20 > what causes it to behave like that and how to fix it. Well, basically you are the only one who can answer that. And that's not a paradox or an attempt at humor. You should investigate. Maybe interrupts aren't processed fast enough (hardware sharing an interrupt?), or memory or kernel resources are low. > for example when lots of spam comes to server and lots of resource hungry= =20 > spamassassin processes are spawned our calls starts to be crappy. >=20 > CPU load for asterisk rarely exceed few percent! Yes, but FreeBSD isn't a _hard_ real-time OS (see below). =20 > i think having separate computer just for this is stupid, i would do this= =20 > having no other choice, but can it be done without this. >=20 > realtime priority is realtime priority anyway - it should work. It does depend what you mean by real-time. Usually real-time systems are devided into the "soft" and "hard" categories. See the Wikipedia article on real-time computing [http://en.wikipedia.org/wiki/Real-time_computing] and operating systems [http://en.wikipedia.org/wiki/Real-time_operating_sys= tem]. Most hard real-time systems are embedded systems with a specific function (say, ECU, FADEC, ABS, digital music player). I don't think there are general use OS's which would classify as hard real-time (AFAIK, RTLinux runs Linux as a low-priority task on a real-time core). Most of them support soft real-time, as in "we'll try to get these tasks done before a specific deadline, but no promises." Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --82I3+IH0IqGh5yIs Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) iEYEARECAAYFAkjqid0ACgkQEnfvsMMhpyXbjwCfTw5/vWdfma2Bm+inj73KFI2L iDoAoKvBm9bRpj+OdHLatDCH9RvFniMF =m6/E -----END PGP SIGNATURE----- --82I3+IH0IqGh5yIs--
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