From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephane Eranian Date: Wed, 30 Jan 2002 06:21:53 +0000 Subject: Re: [Linux-ia64] What's taking all the system time..? Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Duraid, > > I've got a big (production) code that depends on a simple 'graph' > library in C++. To try it out on Itanium, I stripped it down and whipped up > a tiny 'benchmark' of the graph library. When I tried this on an Itanium > system here (2.4.9-SMP, gcc/g++ 2.96/3.0.3 and intel c++ 6.0) the code runs > for about 30 seconds, 20 of which is reported as 'system' time. The thing > is, this is (supposed to be) a CPU-bound job: on my home x86 system, it runs > in about 3 seconds, and with negligible system time. > > 'top' and 'time' show the gobs of system time being used, but > 'strace' picks up nothing out of the ordinary (0.014 seconds system time, > dominated by calls to brk() (this is expected). > Just by curiosity, have you looked at the system log in /var/log/messages? I am guessing your program does some floating point operations. Have you seen something about floating-point software assist? Another potential cause could be unaligned accesses. That you can also see in the system log. -- -Stephane