From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Tizzoni Subject: Re: Re: [Xen-users] About profiling xen Date: Wed, 30 Sep 2009 18:38:26 +0200 Message-ID: References: <7a70c07b-2234-4016-8a44-89edd100228f@default> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <7a70c07b-2234-4016-8a44-89edd100228f@default> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dan Magenheimer Cc: xen , xen-users@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Wed, Sep 30, 2009 at 6:04 PM, Dan Magenheimer wrote: >> How can I get a different, and I hope better, clocksource? In time.c I >> found acpi and hpet are available. > > > I'm no networking expert, but if your packets are > only being processed once per HZ, that seems like > a completely different problem. =A0Even if you are > able to get a hardware high resolution timer, the > resolution has nothing to do with the clock > interrupt frequency (HZ). Netperf use setitimer() to send packets at regular intervals to test network speed. If the timer is not finer enough the signal is not delivered on time and becomes impossibile to reach the requested rate, i.e. if timer is 250Hz you can get at most 250 alarm/s. >>From my point of view this issue should be documented and as well as the clocksource option. I cactched some information googling but it's not clearly explained. m-