linux-kernel - Re: [PATCH v3 -tip 5/5] AHCI: Support multiple MSIs

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Date:	Mon, 01 Oct 2012 23:04:04 -0400
From:	Jeff Garzik <jgarzik@...ox.com>
To:	Alexander Gordeev <agordeev@...hat.com>
CC:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Matthew Wilcox <willy@...ux.intel.com>, x86@...nel.org,
	linux-pci@...r.kernel.org, linux-ide@...r.kernel.org
Subject: Re: [PATCH v3 -tip 5/5] AHCI: Support multiple MSIs

On 10/01/2012 04:13 AM, Alexander Gordeev wrote:
> Take advantage of multiple MSIs implementation on x86 - on systems with
> IRQ remapping AHCI ports not only get assigned separate MSI vectors -
> but also separate IRQs. As result, interrupts generated by different
> ports could be serviced on different CPUs rather than on a single one.
>
> In cases when number of allocated MSIs is less than requested the Sharing
> Last MSI mode does not get used, no matter implemented in hardware or not.
> Instead, the driver assumes the advantage of multiple MSIs is negated and
> falls back to the single MSI mode as if MRSM bit was set (some Intel chips
> implement this strategy anyway - MRSM bit gets set even if the number of
> allocated MSIs exceeds the number of implemented ports).
>
> Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
> ---
>   drivers/ata/ahci.c    |   91 ++++++++++++++++++++++++++++++++++++--
>   drivers/ata/ahci.h    |    6 +++
>   drivers/ata/libahci.c |  118 ++++++++++++++++++++++++++++++++++++++++++++++---
>   3 files changed, 205 insertions(+), 10 deletions(-)

Acked-by: Jeff Garzik <jgarzik@...hat.com>

Normally, this amount of changes would -really- need to go through the 
libata tree.  However, given the amount of dependencies, it either needs 
a merge tree or to go through the PCI tree...?

Any maintainer comments on disposition?

	Jeff




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