From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] kvm-userspace: Make PC speaker emulation aware of in-kernel PIT Date: Sat, 25 Apr 2009 18:28:10 +0200 Message-ID: <49F33A1A.3060201@web.de> References: <49F0CE65.4050005@web.de> <20090425001319.GB15144@amt.cnet> <49F30B55.6050207@codemonkey.ws> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigE2B3F7D3DD5DA4F307EBC249" Cc: Marcelo Tosatti , Avi Kivity , kvm-devel To: Anthony Liguori Return-path: Received: from fmmailgate03.web.de ([217.72.192.234]:33704 "EHLO fmmailgate03.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754239AbZDYQ2R (ORCPT ); Sat, 25 Apr 2009 12:28:17 -0400 In-Reply-To: <49F30B55.6050207@codemonkey.ws> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigE2B3F7D3DD5DA4F307EBC249 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Anthony Liguori wrote: > Marcelo Tosatti wrote: >> Jan, >> >> While the patch itself looks fine, IMO it would be better to move all >> of the timer handling to userspace, except the performance critical >> parts, >> since most of it is generic. Either periodic or one-shot timer, with: >> =20 >=20 > The reason for having the PIT in-kernel is not performance. The PIT is= > not performance sensitive. I think that depends. Some OSes (in some configurations) use the PIT counter as clock source and/or program it regularly in one-shot mode. An aging use case, but still a valid one. >=20 > It's because it was easier to do interrupt catch-up by pushing the PIT > into the kernel which IMHO was the wrong path to go down. Pushing the emulation of port 0x61 into the kernel was a mistake we now have to deal with. I'm not that sure about the PIT itself. Jan --------------enigE2B3F7D3DD5DA4F307EBC249 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAknzOiAACgkQniDOoMHTA+mgEgCdHeXriDI6JhE74WSqMk7gOkGu FNAAn241rNq4PE9Rl7v6b16Vqowxa5Uk =84X2 -----END PGP SIGNATURE----- --------------enigE2B3F7D3DD5DA4F307EBC249--