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Date: Mon, 03 Dec 2012 05:05:30 -0500
From: Jeff Garzik <jgarzik@pobox.com>
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To: Alexander Gordeev <agordeev@redhat.com>
CC: Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Suresh Siddha <suresh.b.siddha@intel.com>,
        Yinghai Lu <yinghai@kernel.org>,
        Matthew Wilcox <willy@linux.intel.com>, x86@kernel.org,
        linux-pci@vger.kernel.org, linux-ide@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 -tip 3/3] AHCI: Support multiple MSIs
References: <cover.1353324359.git.agordeev@redhat.com> <15bf7ee314dd55f21ec7d2a01c47613cd8190a7c.1353324359.git.agordeev@redhat.com>
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On 11/19/2012 10:02 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@redhat.com>
> ---
>   drivers/ata/ahci.c    |   93 +++++++++++++++++++++++++++++++++++++--
>   drivers/ata/ahci.h    |    6 +++
>   drivers/ata/libahci.c |  118 ++++++++++++++++++++++++++++++++++++++++++++++---
>   3 files changed, 207 insertions(+), 10 deletions(-)

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