Re: [PATCH 0/3] Enable multiple MSI feature in pSeries

Michael Ellerman
2013-02-04T03:23:07Z

On Tue, 2013-01-15 at 15:38 +0800, Mike Qiu wrote:
> Currently, multiple MSI feature hasn't been enabled in pSeries,
> These patches try to enbale this feature.

Hi Mike,

> These patches have been tested by using ipr driver, and the driver patch
> has been made by Wen Xiong <wenxiong@linux.vnet.ibm.com>:

So who wrote these patches? Normally we would expect the original author
to post the patches if at all possible.

> [PATCH 0/7] Add support for new IBM SAS controllers

I would like to see the full series, including the driver enablement.

> Test platform: One partition of pSeries with one cpu core(4 SMTs) and
> RAID bus controller: IBM PCI-E IPR SAS Adapter (ASIC) in POWER7
> OS version: SUSE Linux Enterprise Server 11 SP2 (ppc64) with 3.8-rc3 kernel
>
> IRQ 21 and 22 are assigned to the ipr device which support 2 mutiple MSI.
>
> The test results is shown by 'cat /proc/interrups':
> CPU0 CPU1 CPU2 CPU3
> 21: 6 5 5 5 XICS Level host1-0
> 22: 817 814 816 813 XICS Level host1-1

This shows that you are correctly configuring two MSIs.

But the key advantage of using multiple interrupts is to distribute load
across CPUs and improve performance. So I would like to see some
performance numbers that show that there is a real benefit for all the
extra complexity in the code.

cheers