Date: Fri, 31 Jan 2003 10:24:55 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Trish Lynch <trish@bsdunix.net> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Hyperthreading and machdep.cpu_idle_hlt Message-ID: <200301311824.h0VIOtmF095380@apollo.backplane.com> References: <20030131125804.E1357-100000@femme>
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:So, at the request of bmilekic, I ran netpipe on a hyperthreading box (non :hyperthreading, I'll do when I can turn it off in BIOS next time I'm down :there) :... : :The results are here: : :http://bsdunix.net/performance : :all information on what command line options I used is in there. : :the difference with it on is pretty substantial, might be worth noting in :tuning(7) : :-Trish : :-- :Trish Lynch trish@bsdunix.net Those results are indeed quite substantial. Before you modify tuning(7), though, lets wait a bit to see if anyone comes up with a fix to the performance issue when idle_hlt is turned off. In particular I would like to try using a per-cpu global test in the idle loop that avoids doing any locked bus cycles. Unfortunately I am not sure if I have any hyperthreading capable boxes. My primary machine is a pentium 4 but it is running -stable. Timecounter "i8254" frequency 1193182 Hz Timecounter "TSC" frequency 1296069572 Hz CPU: Pentium 4 (1296.07-MHz 686-class CPU) Origin = "GenuineIntel" Id = 0xf07 Stepping = 7 Features=0x3febf9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR,PGE,MCA,CMOV,P AT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,<b28>,ACC> It has HTT set but it's only a 1.2GHz box and I heard somewhere that only 2+ GHz P4's had hyperthreading. I noticed some MFCs to stable that suggested hyperthreading support but I do not know if full hyperthreading support has been MFCd yet or is intended to be MFCd to -stable. -Matt Matthew Dillon <dillon@backplane.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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