From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 08/17] scsi_dh_alua: Make stpg synchronous Date: Mon, 11 May 2015 15:59:34 +0200 Message-ID: <5550B5C6.9010303@suse.de> References: <1430743343-47174-1-git-send-email-hare@suse.de> <1430743343-47174-9-git-send-email-hare@suse.de> <20150511065523.GG30516@lst.de> <55507D74.1070908@suse.de> <20150511135026.GB7795@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:52487 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754144AbbEKN7g (ORCPT ); Mon, 11 May 2015 09:59:36 -0400 In-Reply-To: <20150511135026.GB7795@lst.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig Cc: James Bottomley , linux-scsi@vger.kernel.org, dm-devel@redhat.com On 05/11/2015 03:50 PM, Christoph Hellwig wrote: > On Mon, May 11, 2015 at 11:59:16AM +0200, Hannes Reinecke wrote: >> This is just an intermediate step, before the entire thing moves off >> to a workqueue and becomes asynchronous again. >> It's not meant to be as a standalone patch; I've just split it off >> for easier review. >=20 > It actually made the review a bit harder. Also I don't really undert= and > what the benfit of running a synchronous STPG in a workqueue is over > running it asynchronously. >=20 Because STPG might fail, at which point we need to re-run RTPG to figure out the current status. But that might clash with a scheduled RTPG from another task. _And_ issuing RTPG while STPG is active is pointless, too, as the information is pretty much guaranteed to be incorrect. Hence the use of a workqueue to serialize RTPG and STPG against each other. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: F. Imend=F6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (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