From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <462DC874.20303@domain.hid> Date: Tue, 24 Apr 2007 11:05:56 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <45F68258.5040603@domain.hid> <45F6AA11.40707@domain.hid> <460AB8FF.5060904@domain.hid> <460B21C0.7090200@domain.hid> <460B7FDF.8030100@domain.hid> <460BECFD.2030003@domain.hid> <460C0C7D.7000001@domain.hid> <17964.64208.463335.611234@domain.hid> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig769C0725DCEEC219CDF949CD" Sender: jan.kiszka@domain.hid Subject: Re: [Xenomai-help] Latencies due to RT-Socket-CAN register accesses List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: roland Tollenaar Cc: Xenomai-help@domain.hid This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig769C0725DCEEC219CDF949CD Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable roland Tollenaar wrote: > Hi >=20 >> The latency killers: >> - SMI: check dmesg to see if you get a warning saying that an >> SMI-enabled chipset was detected. If yes, > Yes get this message. >=20 >> read the TROUBLESHOOTING. If > Done what it says here. No change. My latency is also less than 100 us > so this is probably not the problem. Tried anyway but as mentioned, no > difference. >=20 >> - USB: disable legacy USB in BIOS configuration, sometimes it is not > My BIOS settings do not allow me to switch off the USB legacy. At > least I cannot find the place where this is to be done. >=20 >=20 >> enough, and you have to _enable_ USB in kernel configuration, and lo= ad >> the USB modules (that is at least uhci-hcd, ohci-hcd, ehci-hcd and >> usbcore) so that they disable BIOS legacy USB emulation. > These ARE enabled. >=20 >> - X-window: if you see high latencies only when the X server is runnin= g, >> the X-server is probably causing them. A workaround is proposed in t= he >> TROUBLESHOOTING file. > Ran latency without X running. No difference. >=20 >> >> In case all that fails, enable the I-pipe tracer, run latency with the= >> -f option, and check /proc/ipipe/trace/frozen once you observed the hi= gh >> latency in latency. > Have done this and attached the result. I have looked at it myself but > cannot interpret the meaning. >=20 > A bit of help would be appreciated. Two conclusions: - You are running your kernel as i586 without TSC support - suboptimal, costs you a few micros. - The reported latency perfectly matches the trace, nothing pathological there. The trace looks like this: Timer fired, measurement task woken up, two interrupts squeeze themselves between wakeup and time stamp acquisition. All sane. Jan --------------enig769C0725DCEEC219CDF949CD Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGLch0niDOoMHTA+kRAiu3AJsGFmKy6M8zKyT1I0VuV/9I8CFM1wCdHRxP NDtV+7qJheXNgDmOHz1DNsM= =Ac+7 -----END PGP SIGNATURE----- --------------enig769C0725DCEEC219CDF949CD--