linux-kernel - Re: [PATCH V2 3/3] scsi: mptxsas: offload IRQ execution

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Date:	Mon, 09 Nov 2015 08:15:40 +0100
From:	Hannes Reinecke <hare@...e.de>
To:	Sinan Kaya <okaya@...eaurora.org>, linux-scsi@...r.kernel.org,
	timur@...eaurora.org, cov@...eaurora.org, jcm@...hat.com
CC:	agross@...eaurora.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Nagalakshmi Nandigama <nagalakshmi.nandigama@...gotech.com>,
	Praveen Krishnamoorthy <praveen.krishnamoorthy@...gotech.com>,
	Sreekanth Reddy <sreekanth.reddy@...gotech.com>,
	Abhijit Mahajan <abhijit.mahajan@...gotech.com>,
	"James E.J. Bottomley" <JBottomley@...n.com>,
	MPT-FusionLinux.pdl@...gotech.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 3/3] scsi: mptxsas: offload IRQ execution

On 11/09/2015 02:57 AM, Sinan Kaya wrote:
> The mpt2sas and mpt3sas drivers are spinning forever in
> their IRQ handlers if there are a lot of jobs queued up
> by the PCIe card. This handler is causing spikes for
> the rest of the system and sluggish behavior.
> 
> Marking all MSI interrupts as non-shared and moving the
> MSI interrupts to thread context. This relexes the rest
> of the system execution.
> 
NACK.

If there is a scalability issue when handling interrupts
it should be fixed in the driver directly.

Looking at the driver is should be possible to implement
a worker thread handling the reply descriptor, and having the
interrupt only to fetch the reply descriptor.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@...e.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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