From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43BC500D.70202@domain.hid> Date: Wed, 04 Jan 2006 23:45:33 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-core] enjoying the trace References: <43BC430C.5080204@domain.hid> In-Reply-To: <43BC430C.5080204@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig88776C1E3D3A1889E53F8170" 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: xenomai-core This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig88776C1E3D3A1889E53F8170 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Jan Kiszka wrote: > Hi all, > > after a long day of experimenting with a new tracer revision (will get > posted later), I'm looking now for some external wisdom. > > I changed the instrumentation for high-domain stall times such that I > now attach to local_irq_disable_hw & friends instead. In case the > hard-IRQ status doesn't change, only a ipipe_trace_special is issued, a > trace_begin/end otherwise. Additionally, I grab the entering and exiting > of __ipipe_handle_irq and suppress two IRQ on/off points in > arch/i386/kernel/ipipe-root.c. See attached patch (will likely become > part of the tracer). I failed to include the changes of entry.S, see the full patch posted in the related thread. > > Ok, this works significantly better than the previous approach. I just > tormented an Athlon 800 MHz box with Xenomai 2.1 revision 357 (old ipipe > IRQ layer) about 50 minutes with > > latency -p1000 -t1 > dd if=/dev/hda of=/dev/null > ping -f -s 1400 [from external] > cachebench [part of llcbench] > > The result was a maximum latency of 38 us (in-kernel periodic task) and > some traces which correlate quite well. I attached two of them, showing > the similarity between the final and last but one outputs of > /proc/ipipe/trace/max. Note that the instrumentation and the trace > recording add some overhead, how much is just going to be measured. > Result: 33 us without the tracer but otherwise identical boundary conditions. Jan --------------enig88776C1E3D3A1889E53F8170 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 iD8DBQFDvFANniDOoMHTA+kRAnsEAJ9Nt2MsexPiGyjGzCgLynofqoO/0QCfUCxD /dfT4lGCBmUrWSbR/rkAQhQ= =pNws -----END PGP SIGNATURE----- --------------enig88776C1E3D3A1889E53F8170--