From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4B253028.10607@domain.hid> Date: Sun, 13 Dec 2009 19:19:20 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <4B240D0B.50603@domain.hid> <1260723757.2216.2.camel@domain.hid> <4B252909.9090304@domain.hid> <1260727502.2216.19.camel@domain.hid> In-Reply-To: <1260727502.2216.19.camel@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigC55779BE74258F9783B68649" Sender: jan.kiszka@domain.hid Subject: Re: [Adeos-main] [pull request] x86: critical fix for native_safe_halt List-Id: General discussion about Adeos List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: adeos-main This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigC55779BE74258F9783B68649 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Philippe Gerum wrote: > On Sun, 2009-12-13 at 18:48 +0100, Jan Kiszka wrote: >> Philippe Gerum wrote: >>> On Sat, 2009-12-12 at 22:37 +0100, Jan Kiszka wrote: >>>> Recent moving of ipipe_suspend_domain finally exposed a deeper flaw = in >>>> cpu_idle on x86: We failed to check the pipeline log before issuing = the >>>> real hlt. This caused IRQ latencies or even drops for Linux, >>>> specifically on SMP. Credits go to plain QEMU whose slow SMP mode ca= used >>>> ipipe_critical_enter to deadlock frequently enough. >>>> >>>> The first patch of this series fixes this (see below), the second on= e >>>> simply removes the two useless ipipe_suspend_domain calls. >>>> >>> What your patch does as well, is killing the ability to run low prior= ity >>> domains below the root level. >> Yes, I'm killing the dream. >> >> I heavily doubt that the functions I removed in the second patch ever >> contributed something good to this. It's always the job of the lowest >> domain to issue hardware halt, not of some arbitrary mid-prio domain. >> Moreover, what would be the practical use for such model in the contex= t >> of Linux? >=20 > That is _not_ the point. The point is, when submitting a patch, please > make sure to raise all the concerns it might introduce wrt to changing > the base features. I'm not opposed to make the feature set evolve, but = I > don't want this to happen "by mistake". Just pushed "x86: Drop redundant ipipe_suspend_domain from cpu_idle Allowing domains below root always required more than these calls (Linux would have to give up idle management). And syncing the root domain now takes place in __ipipe_halt_root. So remove these suspension calls." as commit message for the second patch. Is that what you are looking for?= Jan --------------enigC55779BE74258F9783B68649 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 iEYEARECAAYFAkslMCwACgkQitSsb3rl5xRwPgCgm8yBf7CUcYCMqyqRoampWqji 9ycAoNt+F5PY9QsP+MGnqJFRF05cWzzT =Mj+e -----END PGP SIGNATURE----- --------------enigC55779BE74258F9783B68649--