| Message ID | 20100131111403.GP2996@kryten (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | 859aefc5afc6c00dae630680e5470f7a2c27c4a0 |
| Delegated to: | Benjamin Herrenschmidt |
| Headers | show |
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
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
On Mon, 2010-02-01 at 10:09 +0100, Gabriel Paubert wrote: > 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. Yeah well, all Anton did was to push up the -max- value you can set in the config, not the default :-) But yeah, it's not "negligible" per-se. Cheers, Ben.
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
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 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> ---