From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4649C8B6.2050304@domain.hid> Date: Tue, 15 May 2007 16:50:30 +0200 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4649A485.5010102@domain.hid> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: Quoted-Printable Subject: Re: [Xenomai-help] memcpy performance on Xenomai List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel Schnell Cc: xenomai@xenomai.org Daniel Schnell wrote: > > -----Original Message----- > > From: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org > > Sent: 15. ma=ED 2007 12:16 > > To: Daniel Schnell > > Cc: xenomai@xenomai.org > > Subject: Re: [Xenomai-help] memcpy performance on Xenomai > > > > > > Improving clock_gettime overhead by reading directly the tsc is my ve= ry next task. If you want to check if the effect you measure is the resul= t of clock_gettime overhead, you can measure the duration of memcpy with = the native api service rt_timer_tsc, and convert the tsc difference with = rt_timer_tsc2ns. >=20 > This was not the culprit. Same results. Does your processor have a tsc ? If yes, do you compile Xenomai with --enable-x86-tsc ? What happens if you disable the interruptions ? >=20 > Does Xenomai replace the memcpy() call with an own implementation ? (I = don't think so.) >=20 > What about trashing of cash lines through context switches ? But then i= f we run it on Linux alone we should also have trashed cache lines. There= should not be any difference. > Is maybe the presence of a Xenomai POSIX thread cause a lot of ctx swit= ches, even if only a memcpy is executed inside the thread ? Shouldn't Xen= omai threads run totally uninterrupted if they have the highest prio ? >=20 > Please could somebody actually run this test on his hardware and see if= these differences between Xenomai POSIX skin and Linux native are happen= ing there as well ? If you want us to test the code, please send it, I mean the one adapted to the native skin. --=20 Gilles Chanteperdrix