From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45D2E1D1.6060407@domain.hid> Date: Wed, 14 Feb 2007 11:17:53 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-help] CONFIG_PREEMPT & irqbench References: <45D25145.3000407@domain.hid> <45D2CE27.5040303@domain.hid> <45D2CF9E.40308@domain.hid> <45D2DD6C.9010005@domain.hid> In-Reply-To: <45D2DD6C.9010005@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig1F3F072983A46A89076F3FA4" Sender: jan.kiszka@domain.hid List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus.Franke@domain.hid Cc: Xenomai-help@domain.hid This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig1F3F072983A46A89076F3FA4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Markus Franke wrote: >> Hmm, I should have better said "tiny". This experience is based on >> I-pipe tracer observations, and I guess you don't have that thing on, >> have you? >=20 > I have set: >=20 > ---snip--- > # CONFIG_IPIPE_DEBUG is not set > CONFIG_IPIPE_TRACE_ENABLE_VALUE=3D0 > ---snap--- >=20 > in both kernels (either with preempt or without). >=20 >> How much is the difference? How long did you measure to exclude noise.= >=20 > The difference is about 1 us (in average and worst case) when running > irqloop in IRQ handler mode. >=20 > I have been running the measurements for 1 minute under heavy load with= > an interrupt frequency of 1 ms. This gives 60000 samples. Is this too > less in order to exclude noise? 1 us is definitely in the noise region even on today's high-end PCs, specifically when running the test that short. 1/2 hour, or better several hours are required to gain reliable worst-case numbers. Regarding the average, your test duration is likely enough. It indicates that CONFIG_PREEMPT worsens the cache hit-rate slightly. Jan --------------enig1F3F072983A46A89076F3FA4 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 iD8DBQFF0uHSniDOoMHTA+kRAs1TAJ9dgA+SaoJR6VY5W5A295W/4zUIwQCggM8r w3C9ZAFLHAGydKzT7QnczVM= =lIKY -----END PGP SIGNATURE----- --------------enig1F3F072983A46A89076F3FA4--