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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dhaval Giani <dhaval@linux.vnet.ibm.com>,
	Mike Travis <travis@sgi.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86_64: Restore the proper NR_IRQS define so larger systems work.
Date: Sat, 02 Aug 2008 23:54:20 -0700	[thread overview]
Message-ID: <4895561C.2030004@goop.org> (raw)
In-Reply-To: <m1sktm7ght.fsf@frodo.ebiederm.org>

Eric W. Biederman wrote:
> Xen pv 64 will work at least as well with a larger definition for
> NR_IRQS as it will work with a smaller definition, and since
> NR_VECTORS is 256 we always have more irqs with the 32bit definition
> we were mistakenly using. 
>
> Xen has 1024 event channels so I expect 1024 would the nice number to
> provide there.
>   

Yes, but really its overkill.  It needs about 6 interrupts/cpu for 
normal system overhead (timer, IPI, things like that), and then some 
amount for virtual devices.

dom0 - the control domain - will need some number of events per other 
guest domain, so it can start feeling the pressure depending on how many 
domains and devices there are.

    J

  reply	other threads:[~2008-08-03  6:54 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-02  2:02 [PATCH] x86: 64bit support more than 256 irq v2 Yinghai Lu
2008-08-02  2:16 ` Yinghai Lu
2008-08-02  2:58   ` Eric W. Biederman
2008-08-02  3:11     ` Yinghai Lu
2008-08-02  3:37       ` Eric W. Biederman
2008-08-04 13:20     ` Mike Travis
2008-08-04 18:16       ` Yinghai Lu
2008-08-03  5:09 ` Eric W. Biederman
2008-08-03  5:26 ` [PATCH] x86_64: Restore the proper NR_IRQS define so larger systems work Eric W. Biederman
2008-08-03  5:58   ` Yinghai Lu
2008-08-03  6:35     ` Eric W. Biederman
2008-08-03  6:54       ` Jeremy Fitzhardinge [this message]
2008-08-03  6:44     ` Jeremy Fitzhardinge

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