There are a number of settings in the Bios of the servers I build can somebody clarify best practice settings for the Xen Cloud 0.5 () = MY SETTINGS PROCESSOR QPI FREQ SELECT (AUTO MAX) QPI TURBO BOOST (ENABLED) ENHANCED INTEL TURBO BOOST (ENABLED) ENHANCED INTEL SPEEDSTEP (R) TECH (ENABLED) TURBO PERFORMANCE BIAS (ENHANCED) PROCESSOR C3 (ACPI C3) PROCESSOR C6 (ENABLED) INTEL HYPER-THREADING TECH (ENABLED) CORE MULTIPROCESSING (ALL) EXECUTE DISABLE BIT (ENABLED) INTEL VT TECH (ENABLED) INTEL VT FOR DIRECTED I/O (DISABLED) HARDWARE PRE-FETCHER (ENABLED) DIRECT CACH ACCESS (DCA) (ENABLED) Regards David Moore moored@romtech.com.au J.P. MCP, MCSE, MCSE + INTERNET, CNE. www.adsldirect.com.au for ADSL and Internet www.romtech.com.au for PC sales Office Phone: (+612) 9453 1990 Fax Phone: (+612) 9453 1880 Mobile Phone: +61(0)424 987 789 Skype Phone: ADSLDIRECT POSTAL ADDRESS: PO BOX 190 BELROSE NSW 2085 AUSTRALIA. --------------------------------------------------------------------- This email message is only intended for the addressee(s) and contains information that may be confidential, legally privileged and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email, or taking any action in reliance on its contents by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --------------------------------------------------------------------- _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Matej Zary
2010-Jul-23 19:06 UTC
Re: Re: [Xen-users] XEON 5640 ENABLE C3 / C6 and other settings
On Sat, 2010-07-24 at 01:09 +1000, David Moore wrote:> There are a number of settings in the Bios of the servers I build can somebody clarify best practice settings for the Xen Cloud 0.5 > > () = MY SETTINGS > > PROCESSOR QPI FREQ SELECT (AUTO MAX) > QPI TURBO BOOST (ENABLED) > ENHANCED INTEL TURBO BOOST (ENABLED) > ENHANCED INTEL SPEEDSTEP (R) TECH (ENABLED) > TURBO PERFORMANCE BIAS (ENHANCED) > PROCESSOR C3 (ACPI C3) > PROCESSOR C6 (ENABLED) > INTEL HYPER-THREADING TECH (ENABLED) > CORE MULTIPROCESSING (ALL) > EXECUTE DISABLE BIT (ENABLED) > INTEL VT TECH (ENABLED) > INTEL VT FOR DIRECTED I/O (DISABLED) > HARDWARE PRE-FETCHER (ENABLED) > DIRECT CACH ACCESS (DCA) (ENABLED) > > > > > Regards David Moore > moored@romtech.com.au > > J.P. MCP, MCSE, MCSE + INTERNET, CNE. > www.adsldirect.com.au for ADSL and Internet www.romtech.com.au for PC sales > > Office Phone: (+612) 9453 1990 > Fax Phone: (+612) 9453 1880 > Mobile Phone: +61(0)424 987 789 > Skype Phone: ADSLDIRECT > > POSTAL ADDRESS: > PO BOX 190 > BELROSE NSW 2085 > AUSTRALIA.Hi there, I'm not expert in this area, but as far i remember, using Hyper Threading in Xen used to be counterproductive, because the fake HT cores doesn't have own processing power (if this has changed, somebody correct me please! :) ). Also the INTEL VT FOR DIRECTED I/O functionality might be useful for pci-passthru scenarios. (truth to be said, if you are going for XCP, I guess you will be not using pci-passthru ) Regards Matej _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Javier Guerra Giraldez
2010-Jul-23 19:32 UTC
Re: Re: [Xen-users] XEON 5640 ENABLE C3 / C6 and other settings
On Fri, Jul 23, 2010 at 2:06 PM, Matej Zary <matej.zary@cvtisr.sk> wrote:> I''m not expert in this area, but as far i remember, using Hyper > Threading in Xen used to be counterproductive, because the fake HT cores > doesn''t have own processing power (if this has changed, somebody correct > me please! :) ).these are not ''fake cores''; they''re extra execution threads in a core. the idea is to increment the number of non-dependent instructions available to the OOOexecution unit; so when some part of the CPU is busy (likely waiting for RAM, or a complex ALU operation), it can do other useful work. kinda like at the OS level some processes can advance while others are waiting for IO (like hard disk). at the CPU level, one thread can advance while the other is waiting for RAM. the end result is to reduce the frequency of pipeilne bubbles that can stall the whole chip. in the pentium era (with absurdly long pipelines) it had a very noticeable advantage when the OS had enough threads to keep the CPU busy. only on heavy single-threaded applications the overhead becomes larger than the advantage; i think gamers of the time tended to shun hyperthreading because all games were singlethreaded. nowadays i don''t know if it''s less important (because pipelines aren''t so deep) or more important (because a greater mismatch between RAM and CPU access speeds), in any case, on servers you''re almost guaranteed to have lots of runnable threads, so hyperthreading does benefit the majority of cases. in Xen specific case, you''re even more likely to have lots and lots of threads available to the CPU making hyperthreading happy. and two extra benefits: with more threads, you have finer granularity to assign CPU power to your DomU''s. second, (maybe more important) on heavy IO setups you might have to dedicate a CPU exclusively to Dom0 to eliminate domain switches, and dedicating a thread is less expensive than dedicating a core. -- Javier _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users