From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Vasquez Subject: Re: Interrupts are being dropped under heavy IO on -rt . Date: Wed, 15 Apr 2009 12:48:02 -0700 Message-ID: <20090415194802.GD1382@plap4-2.local> References: <49DF71CF.7070509@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: LKML , rt-users , Mike Anderson , "Luis Claudio R. Goncalves" , Linux Driver To: jvrao Return-path: Received: from avexch1.qlogic.com ([198.70.193.115]:51551 "EHLO avexch1.qlogic.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754769AbZDOTsE (ORCPT ); Wed, 15 Apr 2009 15:48:04 -0400 Content-Disposition: inline In-Reply-To: <49DF71CF.7070509@linux.vnet.ibm.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Fri, 10 Apr 2009, jvrao wrote: > Qlogic driver uses MSI-EDGE interrupts by default. > > On -rt kernel under heavy IO load we observed that the driver missed > interrupts occasionally. > > Missing interrupts caused spurious mailbox timeouts and path failovers. > > Suspecting MSI interrupts, we disabled MSI and forcing the driver to use > APIC interrupts (Patch attached). > > With this change, our IO tests ran for extended period of time without > any issues. > > It would be interesting to see if the MSI infrastructure itself has > issues on realtime, or it is the combination of qla2xxx/MSI. > > Right now we don't have any setup to test out MSI with other adapters. > Hence, wondering if anyone faced similar issues. Could you perhaps provide some details on hardware used within your testing -- HBA type, storage, etc? Also, can you share any logs of the failures with extended-error-logging enabled (ql2xextended_error_logging)? Regards, Andrew Vasquez