linux-kernel - Re: [PATCH v4 -tip 3/3] AHCI: Support multiple MSIs

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Message-ID: <20121025090957.GA7424@gmail.com>
Date:	Thu, 25 Oct 2012 11:09:57 +0200
From:	Ingo Molnar <mingo@...nel.org>
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>,
	Jeff Garzik <jgarzik@...ox.com>,
	Matthew Wilcox <willy@...ux.intel.com>, x86@...nel.org,
	linux-pci@...r.kernel.org, linux-ide@...r.kernel.org
Subject: Re: [PATCH v4 -tip 3/3] AHCI: Support multiple MSIs


* Alexander Gordeev <agordeev@...hat.com> 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    |   93 +++++++++++++++++++++++++++++++++++++--
>  drivers/ata/ahci.h    |    6 +++
>  drivers/ata/libahci.c |  118 ++++++++++++++++++++++++++++++++++++++++++++++---
>  3 files changed, 207 insertions(+), 10 deletions(-)

Has Jeff acked this patch?

Thanks,

	Ingo
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