From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryan Underwood Subject: Re: dosemu with different speed Date: Sat, 24 Apr 2004 19:00:22 -0500 Sender: linux-msdos-owner@vger.kernel.org Message-ID: <20040425000022.GC24996@dbz.icequake.net> References: <20040420081426.92814.qmail@web11707.mail.yahoo.com> <20040423195728.GE31941@dbz.icequake.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="O3RTKUHj+75w1tg5" Return-path: Content-Disposition: inline In-Reply-To: <20040423195728.GE31941@dbz.icequake.net> List-Id: To: linux-msdos@vger.kernel.org --O3RTKUHj+75w1tg5 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Apr 24, 2004 at 09:32:39PM +0100, Andrew Brooks wrote: > Ryan Underwood wrote: > > What do you mean by "speed"? You want different scheduling > > priorities > > for each one? Can just use 'nice'. =20 > > I have a DOS application which must respond to an interrupt within a > certain amount of time. I have tried using nice to raise the priority > but it still misses occasionally. Yep. DOSEMU is not DOS. If you have realtime constraints, we must look into calling sched_setscheduler() on user's behalf to set policy to SCHED_RR or SCHED_FIFO. But that will require root permission. It is also possible for your machine to be completely locked-up if the DOS task fails in any way. > Do you think it's safe to run dosemu in the realtime scheduling class? > (in which case I would leave hogthreshold at 1 =3D nicest) I think DOSEMU itself is mostly safe. The problem is the DOS program you are running. If it ever goes into an uncontrollable loop (i.e. polling with interrupts disabled), you are screwed and will have to reboot when running SCHED_FIFO. SCHED_RR should not be so bad because the scheduler is guaranteed to seize control periodically, but only other SCHED_RR processes are guaranteed to get any CPU time. So you would have to have a SCHED_RR bash running too in order to be able to gain control of the other process. --=20 Ryan Underwood, --O3RTKUHj+75w1tg5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQFAiv+WIonHnh+67jkRAtMgAJ40pWpopSHM6G5YI685K2h0RWDnNACfenXA FIczxuzLNkiVkY23xRtkzOw= =U1pA -----END PGP SIGNATURE----- --O3RTKUHj+75w1tg5--