Re: take7: vector sharing (Large I/O system support)

[Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>]

Hi Cristoph,

>>+config NR_RTE_CACHES
>>+	int "Number of RTE cache entries"
>>+	depends on IOSAPIC
>>+	default "256"
>>+	help
>>+	  If your system panic with the message "out of rte cache
>>+	  entries!(shortage: XX)", please set this to a larger value.
> 
> 
> This screams for dynamic allocation of the underlying structures, no?

Some number (NR_RTE_CACHES) of iosapic_rte_info structures are
statically allocated because this structure might be needed before
kmalloc is initialized. The panic message mentioned above means we
run out of these statically allocated structures.

Thanks,
Kenji Kaneshige
 

Christoph Hellwig wrote:
> On Mon, Feb 28, 2005 at 09:58:54AM +0900, Kenji Kaneshige wrote:
> 
>>Hi Tony,
>>
>>I had a good discussion about vector sharing patch with
>>Ashok Raj (Thank you Ashok!!) and I made change to it based
>>on the comments from him.
>>
>>Summary of Changes are:
>>  - Removed sharable flag from iosapic_itr_info structure
>>  - Made NR_RTE_CACHE_ENTRIES configurable
>>
>>Attached patch is against 2.6.11-rc5.
>>
>>Thanks,
>>Kenji Kaneshige
>>
>>
>>Current ia64 linux cannot handle greater than 184 interrupt sources
>>because of the lack of vectors. The following patch enables ia64 linux
>>to handle greater than 184 interrupt sources by allowing the same
>>vector number to be shared by multiple IOSAPIC's RTEs. The design of
>>this patch is besed on "Intel(R) Itanium(R) Processor Family Interrupt
>>Architecture Guide".
>>
>>Even if you don't have a large I/O system, you can see the behavior of
>>vector sharing by changing IOSAPIC_LAST_DEVICE_VECTOR to fewer value.
>>
>>Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
>>
>>
>>---
>>
>> linux-2.6.11-rc5-kanesige/arch/ia64/Kconfig           |    8 
>> linux-2.6.11-rc5-kanesige/arch/ia64/kernel/iosapic.c  |  356 +++++++++++++-----
>> linux-2.6.11-rc5-kanesige/arch/ia64/kernel/irq_ia64.c |   16 
>> linux-2.6.11-rc5-kanesige/include/asm-ia64/hw_irq.h   |    1 
>> 4 files changed, 291 insertions(+), 90 deletions(-)
>>
>>diff -puN arch/ia64/Kconfig~vector_sharing arch/ia64/Kconfig
>>--- linux-2.6.11-rc5/arch/ia64/Kconfig~vector_sharing	2005-02-25 09:08:18.000000000 +0900
>>+++ linux-2.6.11-rc5-kanesige/arch/ia64/Kconfig	2005-02-25 09:08:18.000000000 +0900
>>@@ -318,6 +318,14 @@ config ACPI_DEALLOCATE_IRQ
>> 	depends on IOSAPIC && EXPERIMENTAL
>> 	default y
>> 
>>+config NR_RTE_CACHES
>>+	int "Number of RTE cache entries"
>>+	depends on IOSAPIC
>>+	default "256"
>>+	help
>>+	  If your system panic with the message "out of rte cache
>>+	  entries!(shortage: XX)", please set this to a larger value.
> 
> 
> This screams for dynamic allocation of the underlying structures, no?
> 
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