From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43AAC0A2.7020409@domain.hid> Date: Thu, 22 Dec 2005 16:05:06 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-core] [bug] don't try this at home... References: <438DD4E2.9080208@domain.hid> <438DE166.5090303@domain.hid> <438DE551.7080708@domain.hid> <43A32305.8030004@domain.hid> <43A329E6.3080505@domain.hid> <43A34F6C.6020904@domain.hid> <43A56A44.6020308@domain.hid> <43A5AACF.6050505@domain.hid> In-Reply-To: <43A5AACF.6050505@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig530A61FB81BB1936F8EF75E8" Sender: jan.kiszka@domain.hid List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: xenomai@xenomai.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig530A61FB81BB1936F8EF75E8 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Philippe Gerum wrote: > Jan Kiszka wrote: >> ... >> Anyway, there seems to be some latency issues pending. I discovered this >> again with my migration test. Please give it a try on a mid- (800 MHz >> Athlon in my case) to low-end box. On that Athlon I got peaks of over >> 100 us in the userspace latency test right on starting migration. The >> Athlon does not support the NMI watchdog, but on my 1.4 GHz Notebook >> there were alarms (>30 us) hitting in the native registry during >> rt_task_create. I have no clue yet if anything is broken there. > > > I suspect that rt_registry_enter() is inherently a long operation when > considered as a non-preemptible sum of reasonably short ones. Since it > is always called with interrupts enabled, we should split the work in > there, releasing interrupts in the middle. The tricky thing is that we > must ensure that the new registration slot is not exposed in a > half-baked state during the preemptible section. > Grr, I should stop profiling systems which have DEBUG options switched on (e.g. Xenomain's queue debugging...). This totally skrewed up my measurings - end of alarm, all fine! Anyway, keeping the number of ops inside continues lock paths low is a good thing. But if the task deletions path is already one of the most critical points, needs some analysis first. Jan --------------enig530A61FB81BB1936F8EF75E8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDqsCjniDOoMHTA+kRAqQRAJ9qfW4cTOTWadYZAM2OMoJd4YTawwCbBT9k IYUOMZHlxOT0PueR1Yw/v3I= =+8ic -----END PGP SIGNATURE----- --------------enig530A61FB81BB1936F8EF75E8--