From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 0/3] megaraid_sas: Convert to host_lock less w/ interrupts disabled internally Date: Mon, 29 Nov 2010 16:56:18 +0100 Message-ID: <4CF3CD22.2050504@suse.de> References: <1290928656-31116-1-git-send-email-nab@linux-iscsi.org> <1290929339.6216.188.camel@haakon2.linux-iscsi.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:52143 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754140Ab0K2PxJ (ORCPT ); Mon, 29 Nov 2010 10:53:09 -0500 In-Reply-To: <1290929339.6216.188.camel@haakon2.linux-iscsi.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Nicholas A. Bellinger" Cc: linux-scsi , Bo Yang , Christoph Hellwig , James Bottomley On 11/28/2010 08:28 AM, Nicholas A. Bellinger wrote: > On Sat, 2010-11-27 at 23:17 -0800, Nicholas A. Bellinger wrote: >> From: Nicholas Bellinger >> >> Greetings Hannes, Bo and Co, >> >> This series converts megaraid_sas to run in modern host_lock-less mo= de >> for >=3D .37-rc3+ with interrupts disabled internally around megasas= _instance->hba_lock. >> This series is currently living in lio-core-2.6.git/lock_less-LLDs-f= or-38-v2, >> and is intended for .38 mainline code. >> >> The first patch adds a handful of missing barriers around instance->= fw_outstanding >> usage w/ atomic_add() and atomic_dec(). >> >> The second converts instance->issuepend_done to an atomic_t, along w= ith >> the necessary assignments in order to run w/ Scsi_Host->host_lock, a= nd >> without instance->hba_lock. >> >> The third patch does the actual conversion, and adds a __megasas_get= _cmd() >> usased by megasas_queue_command() w/ instance->hba_lock, along with >> being held for megasas_build_ldio() and megasas_build_dcdb() in orde= r >> to locate the proper frame for struct megasas_cmd. This is really t= he >> one major change in order to get host_lock-less to function with int= errupts >> disabled around hba_lock. >> >> So far this has been tested with Hannes's QEMU 8708EM2 HBA emulation= with >> TCM_Loop backends using SG_IO from KVM host in a paired Host/Guest .= 37-rc3 >> environment. This has not been tested on real silicon yet, but I be= lieve >> this series should be working there as well. >> >=20 > And quick screenshot running in KVM Host TCM_Loop host_lock-less mode > into KVM Guest megaraid_sas host_lock-less mode w/ small block LTP > disktest. >=20 > http://www.linux-iscsi.org/index.php/File:TCM_loop-megasas-37-rc3.png >=20 > Just a FYI, with scsi-generic <-> TCM_Loop everything appears to be > stable for both small and large block size tests. >=20 Oh, good. I did some initial tests with megaraid_sas & host_lock disabled, but ran into the problems you mentioned. And have been too lazy to pursue this problem further. Thanks for your work; I'll give it a spin and see if the throughput speed has increased. Thanks for the patches. Btw, I've found one issue wrt Windows7 booting; now we're not crashing anymore. But we're not exactly progressing, either; apparently Win7 fails to notify that we've finished the commands. Continue debugging. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html