From: Gabriel Paubert <paubert@iram.es>
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, 1 Feb 2010 10:09:46 +0100 [thread overview]
Message-ID: <20100201090946.GA22966@iram.es> (raw)
In-Reply-To: <20100131111403.GP2996@kryten>
On Sun, Jan 31, 2010 at 10:14:03PM +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:
Only 1/2 MB?
I'm running Linux on 12 year old PPC machines which have 16MB
or RAM (ok, they are still running an old kernel, but a few
patches like this and they wont't even boot). The kernels
I have are well below 1MB, code+data+bss.
Yes it is configurable, thanks, and 64 is enough for these
machines (8259 plus an MPIC), so it's not that crucial.
What I object to is calling 1/2MB negligible.
Gabriel
next prev parent reply other threads:[~2010-02-01 9:10 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
2010-02-01 9:09 ` Gabriel Paubert [this message]
2010-02-01 10:04 ` Benjamin Herrenschmidt
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