RE: "Hyperthreading"
well I got a 3.06ghz ht cpu, and redhat 9 with the latest kernel simply keeps saying I got only 1 CPU.. no 2 (virtual ones) it installed the smp kernel though.. so I guess at least it detected it during installation. windows xp on the same machine has no problems whatsoever detecting and using both virtual cpus, tried different bioses etc.. but no worky :( -j -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Laurent GUERBY Sent: Tuesday, August 19, 2003 12:51 PM To: [EMAIL PROTECTED] Subject: Re: "Hyperthreading" On Tue, 2003-08-19 at 12:16, James Olin Oden wrote: > I think 2.4.18 of the linux kernel and beyond do so, and specifically > RH 9 supports hyper threading right out of the box. I have been using > it on some boxes supporting hyperthreading without any issues since > the RH 9 beta came out (phoebe). It works with Red Hat 7.3 too. The only problem is on biprocessor HT boxes, if you launch two processes that take 100% CPU, the kernel might schedule both of them on the same physical processor which gives horrible and unpredictable performance for the box. On one HT processor, both processes will be on the same physical processor (no choice :), but scheduling will be very unfair, assuming same total computation time, one will finish much earlier than the other. I don't know if these two problems are solved with more recent kernels, information anyone? Laurent ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list
Re: "Hyperthreading"
On Tue, 2003-08-19 at 12:16, James Olin Oden wrote: > I think 2.4.18 of the linux kernel and beyond do so, and specifically RH 9 > supports hyper threading right out of the box. I have been using it on > some boxes supporting hyperthreading without any issues since the RH 9 > beta came out (phoebe). It works with Red Hat 7.3 too. The only problem is on biprocessor HT boxes, if you launch two processes that take 100% CPU, the kernel might schedule both of them on the same physical processor which gives horrible and unpredictable performance for the box. On one HT processor, both processes will be on the same physical processor (no choice :), but scheduling will be very unfair, assuming same total computation time, one will finish much earlier than the other. I don't know if these two problems are solved with more recent kernels, information anyone? Laurent ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list
Re: "Hyperthreading"
On Mon, 18 Aug 2003, Richard Troy wrote: > > > Hi guys, > > I'm just wondering: We just recently - last weekend - decided to "move > into the modern era" on one of our server boxes running RedHat Linux. Our > hardware selection was P4 2.6ghz, 800mhz fsb, with a gig of main memory on > an Intel brand mother board with integrated 1000 Base-T nic. Along the > way, I noticed that the bios has an option to turn on or off > "Hyperthreading" - which I presume is just a flavor of pipelining - and > the supporting documentation warns to not use hyperthreading if your OS > does not support it... > > OK, you saw it coming a mile away: What versions of Linux, if any, support > hyperthreading? If not, any idea when? > I think 2.4.18 of the linux kernel and beyond do so, and specifically RH 9 supports hyper threading right out of the box. I have been using it on some boxes supporting hyperthreading without any issues since the RH 9 beta came out (phoebe). Cheers...james > Thanks, > Richard > > P.S. In a similar vein: I know we _were_ limited to around 120gb disks > with, say RedHat 7.2. Does this limitation still apply? (I vaguely recall > it had to do with lack of support for ATA-133, IIRC.) If not, got any > details? Thanks again, RT > > ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list
Re: "Hyperthreading"
> > Hi guys, > > > > I'm just wondering: We just recently - last weekend - decided to "move > > into the modern era" on one of our server boxes running RedHat Linux. Our > > hardware selection was P4 2.6ghz, 800mhz fsb, with a gig of main memory on > > an Intel brand mother board with integrated 1000 Base-T nic. Along the > > way, I noticed that the bios has an option to turn on or off > > "Hyperthreading" - which I presume is just a flavor of pipelining - and > > the supporting documentation warns to not use hyperthreading if your OS > > does not support it... > > > > OK, you saw it coming a mile away: What versions of Linux, if any, support > > hyperthreading? If not, any idea when? > > I believe hyperthreading is fine with the latest kernels: you want SMP. > However, I am not sure you actually have it: it came in on the non-Xeon > CPUs when they reached/passed 3 Ghz, and I don't know whether Intel > introduced new slower CPUs with it. The fact you have the BIOS option is > a good indicator that the mobo supports those CPUs, but whether you have > one is another question. > On the three P4s I just bought, there's absolutely no question: They have hyperthreading. They're all 2.6 ghz, two with 533 mhz fsb, one with 800 mhz. RT ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list
Re: "Hyperthreading"
On Mon, 18 Aug 2003, Richard Troy wrote: > > > Hi guys, > > I'm just wondering: We just recently - last weekend - decided to "move > into the modern era" on one of our server boxes running RedHat Linux. Our > hardware selection was P4 2.6ghz, 800mhz fsb, with a gig of main memory on > an Intel brand mother board with integrated 1000 Base-T nic. Along the > way, I noticed that the bios has an option to turn on or off > "Hyperthreading" - which I presume is just a flavor of pipelining - and > the supporting documentation warns to not use hyperthreading if your OS > does not support it... > > OK, you saw it coming a mile away: What versions of Linux, if any, support > hyperthreading? If not, any idea when? I believe hyperthreading is fine with the latest kernels: you want SMP. However, I am not sure you actually have it: it came in on the non-Xeon CPUs when they reached/passed 3 Ghz, and I don't know whether Intel introduced new slower CPUs with it. The fact you have the BIOS option is a good indicator that the mobo supports those CPUs, but whether you have one is another question. -- Please, reply only to the list. Join the "Linux Support by Small Businesses" list at http://mail.computerdatasafe.com.au/mailman/listinfo/lssb ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list
Re: "Hyperthreading"
I don't know about >120GB drives, however, Hyperthreading works in the recent Red Hat released 2.4 kernels. I'm not sure if that's a back port from 2.6 or what. What happens is the kernel sees 2*n processors where n is the number of physical processors in the machine. I.e. if you have a 2 proc 2.4 Ghz, the kernel will see 4 processors. I'm sure that you'd have to run the SMP kernel even on a single proc machine. Joseph Richard Troy wrote: Hi guys, I'm just wondering: We just recently - last weekend - decided to "move into the modern era" on one of our server boxes running RedHat Linux. Our hardware selection was P4 2.6ghz, 800mhz fsb, with a gig of main memory on an Intel brand mother board with integrated 1000 Base-T nic. Along the way, I noticed that the bios has an option to turn on or off "Hyperthreading" - which I presume is just a flavor of pipelining - and the supporting documentation warns to not use hyperthreading if your OS does not support it... OK, you saw it coming a mile away: What versions of Linux, if any, support hyperthreading? If not, any idea when? Thanks, Richard P.S. In a similar vein: I know we _were_ limited to around 120gb disks with, say RedHat 7.2. Does this limitation still apply? (I vaguely recall it had to do with lack of support for ATA-133, IIRC.) If not, got any details? Thanks again, RT ___ Redhat-devel-list mailing list [EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-devel-list
