From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Anton Blanchard <anton@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 5/5] powerpc: Increase NR_IRQS Kconfig maximum to 32768
Date: Mon, 01 Feb 2010 07:35:24 +1100 [thread overview]
Message-ID: <1264970124.8287.9.camel@pasglop> (raw)
In-Reply-To: <20100131111403.GP2996@kryten>
On Sun, 2010-01-31 at 22:14 +1100, Anton Blanchard wrote:
> With dynamic irq descriptors the overhead of a large NR_IRQS is much lower
> than it used to be. With more MSI-X capable adapters and drivers exploiting
> multiple vectors we may as well allow the user to increase it beyond the
> current maximum of 512.
>
> 32768 seems large enough that we'd never have to bump it again (although I bet
> my prediction is horribly wrong). It boot tests OK and the vmlinux footprint
> increase is only around 500kB due to:
>
> struct irq_map_entry irq_map[NR_IRQS];
We could dynamically allocate that one.
Cheers,
Ben.
> We format /proc/interrupts correctly with the previous changes:
>
> CPU0 CPU1 CPU2 CPU3 CPU4 CPU5
> 286: 0 0 0 0 0 0
> 516: 0 0 0 0 0 0
> 16689: 1833 0 0 0 0 0
> 17157: 0 0 0 0 0 0
> 17158: 319 0 0 0 0 0
> 25092: 0 0 0 0 0 0
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---
>
> Index: linux-cpumask/arch/powerpc/Kconfig
> ===================================================================
> --- linux-cpumask.orig/arch/powerpc/Kconfig 2010-01-31 15:07:11.707211107 +1100
> +++ linux-cpumask/arch/powerpc/Kconfig 2010-01-31 21:52:39.999711689 +1100
> @@ -58,7 +58,7 @@ config IRQ_PER_CPU
>
> config NR_IRQS
> int "Number of virtual interrupt numbers"
> - range 32 512
> + range 32 32768
> default "512"
> help
> This defines the number of virtual interrupt numbers the kernel
next prev parent reply other threads:[~2010-01-31 20:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-31 11:09 [PATCH 1/5] powerpc: Rework /proc/interrupts Anton Blanchard
2010-01-31 11:10 ` [PATCH 2/5] powerpc: Remove whitespace in irq chip name fields Anton Blanchard
2010-01-31 11:11 ` [PATCH 3/5] powerpc: Add timer, performance monitor and machine check counts to /proc/interrupts Anton Blanchard
2010-01-31 11:13 ` [PATCH 4/5] powerpc: Convert global "BAD" interrupt to per cpu spurious Anton Blanchard
2010-01-31 11:14 ` [PATCH 5/5] powerpc: Increase NR_IRQS Kconfig maximum to 32768 Anton Blanchard
2010-01-31 20:35 ` Benjamin Herrenschmidt [this message]
2010-02-01 9:09 ` Gabriel Paubert
2010-02-01 10:04 ` Benjamin Herrenschmidt
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