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xen-devel
[Xen-devel] Re: [RFC, PATCH 24/24] i386 Vmi no idle hz
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To: |
Zachary Amsden <zach@xxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: [RFC, PATCH 24/24] i386 Vmi no idle hz |
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From: |
Pavel Machek <pavel@xxxxxx> |
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Date: |
Thu, 16 Mar 2006 00:31:28 +0100 |
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Cc: |
Andrew Morton <akpm@xxxxxxxx>, Joshua LeVasseur <jtl@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Pratap Subrahmanyam <pratap@xxxxxxxxxx>, Wim Coekaerts <wim.coekaerts@xxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxx>, Jack Lo <jlo@xxxxxxxxxx>, Dan Hecht <dhecht@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx>, Christopher Li <chrisl@xxxxxxxxxx>, Virtualization Mailing List <virtualization@xxxxxxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxx>, Anne Holler <anne@xxxxxxxxxx>, Jyothy Reddy <jreddy@xxxxxxxxxx>, Kip Macy <kmacy@xxxxxxxxxxx>, Ky Srinivasan <ksrinivasan@xxxxxxxxxx>, Leendert van Doorn <leendert@xxxxxxxxxxxxxx>, Dan Arai <arai@xxxxxxxxxx> |
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Fri, 17 Mar 2006 10:49:58 +0000 |
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Mutt/1.5.9i |
Hi!
> When a VCPU enters its idle loop, it disables its periodic
> alarm and sets up a one shot alarm for the next time event.
> That way, it does not become ready to run just to service
> the periodic alarm interrupt. Instead, it can remain halted
> until there is some real work pending for it. This allows
> the hypervisor to use the physical resources more
> effectively since idle VCPUs will have lower overhead.
Does this NO_IDLE_HZ work only on VMI-enabled runs or globally? We are
trying to get NO_IDLE_HZ working to save some power on notebooks; how
is it related to this?
> @@ -579,6 +569,17 @@ static ctl_table kern_table[] = {
> .proc_handler = &proc_dointvec,
> },
> #endif
> +#if defined(CONFIG_NO_IDLE_HZ) && (defined(CONFIG_ARCH_S390) || \
> + defined(CONFIG_X86) &&
> defined(CONFIG_X86_VMI))
> + {
> + .ctl_name = KERN_HZ_TIMER,
> + .procname = "hz_timer",
> + .data = &sysctl_hz_timer,
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = &proc_dointvec,
> + },
> +#endif
> {
> .ctl_name = KERN_PIDMAX,
> .procname = "pid_max",
But this seems to disable it for non-VMI machines :-(.
> Index: linux-2.6.16-rc6/include/asm-i386/mach-default/mach_idletimer.h
> ===================================================================
> --- linux-2.6.16-rc6.orig/include/asm-i386/mach-default/mach_idletimer.h
> 2006-03-12 19:57:53.000000000 -0800
> +++ linux-2.6.16-rc6/include/asm-i386/mach-default/mach_idletimer.h
> 2006-03-12 19:57:53.000000000 -0800
> @@ -0,0 +1,19 @@
> +
> +/*
> + * NO_IDLE_HZ callbacks.
> + */
> +
> +#ifndef __ASM_MACH_IDLETIMER_H
> +#define __ASM_MACH_IDLETIMER_H
> +
> +static inline void stop_hz_timer(void)
> +{
> +
> +}
> +
> +static inline void restart_hz_timer(struct pt_regs *regs)
> +{
> +
> +}
> +
> +#endif /* __ASM_MACH_IDLETIMER_H */
And I guess these would need to be implemented.
Can you use NO_IDLE_HZ patches that are already floating around?
Pavel
--
180: alg = Rijndael.Create();
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