RE: Pentium 4 hyperthreading
Ben, With Xeon, I'm using NUMCPUVPS=8 on 4-CPU (real CPU's) Linux box (2 GHz Xeons, 2MB L3 cache). Everything works fantastic. It's not clear to me, whether Linux process scheduling takes into account that some CPU's are 'better' then others. If You set NUMCPUVPS as number of virtual CPU's You shouldn't really care about load balancing. AFAIK KAIO is not supported in the Linux ports of IDS, even though some latest Linux kernels might support it. Frankly speaking, everything works very well even without KAIO. In my opinion, one should use KAIO only on those platforms, where it is really well implemented: SUM, AIX and NT. Never HPUX. ------------------------------------------ Alexey Sonkin Senior Database Administrator > -----Original Message----- > From: Ben Thompson [mailto:ben@nomonitorsoftspamthanks.com] > Sent: Friday, January 30, 2004 10:54 AM > To: informix-list@iiug.org > Subject: Pentium 4 hyperthreading > > I was wondering about appropriate onconfig settings for Pentium 4 Xeon > processors with hyper-threading. Linux seems to treat a Pentium 4 Xeon > as two processors: when you cat /proc/cpuinfo you see twice as many CPUs > as you actually have. > > So when setting up the VPCLASS parmater in onconfig should you treat a > single Xeon as one or two CPUs. I would guess two since the OS is > certainly reporting two to applications. Does anyone know for sure or > can anyone point me to an appropriate document on the subject? > > I am using Linux 9.40.UC2 on SuSE Linux 9.0, kernel 2.4.21-166-smp4G, > glibc 2.3.2-87. > > Also, is there any way of getting KAIO working with this combination. > The stock SuSE kernel supports this feature unlike the standard Linux > kernel. I have tried setting the KAIO environment variables but it > doesn't work so I imagine the answer is a no. This is afterall what the > release notes suggest. > > Ben. sending to informix-list
Alexey Sonkin <alexeis@grandvirtual.com> writes: > With Xeon, I'm using NUMCPUVPS=8 on 4-CPU (real CPU's) > Linux box (2 GHz Xeons, 2MB L3 cache). Everything works fantastic. > > It's not clear to me, whether Linux process scheduling > takes into account that some CPU's are 'better' then others. > If You set NUMCPUVPS as number of virtual CPU's You shouldn't > really care about load balancing. The hyperthreading-friendly scheduler is supposed to be in the 2.6 kernel. Red Hat might have backported it to the 2.4 kernel in RHL9 or RHEL3, but I haven't checked. -- Forte International, P.O. Box 1412, Ridgecrest, CA 93556-1412 Ronald Cole <ronald@forte-intl.com> Phone: (760) 499-9142 President, CEO Fax: (760) 499-9152 My GPG fingerprint: C3AF 4BE9 BEA6 F1C2 B084 4A88 8851 E6C8 69E3 B00B