From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH v3] storvsc: use small sg_tablesize on x86 Date: Thu, 09 Jun 2016 10:25:59 -0700 Message-ID: <1465493159.2259.14.camel@linux.vnet.ibm.com> References: <20160609162553.10290-1-olaf@aepfle.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58619 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751393AbcFIR0K (ORCPT ); Thu, 9 Jun 2016 13:26:10 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u59HNmB3077783 for ; Thu, 9 Jun 2016 13:26:09 -0400 Received: from e33.co.us.ibm.com (e33.co.us.ibm.com [32.97.110.151]) by mx0a-001b2d01.pphosted.com with ESMTP id 23e9m51ym2-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 09 Jun 2016 13:26:09 -0400 Received: from localhost by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 9 Jun 2016 11:26:08 -0600 In-Reply-To: <20160609162553.10290-1-olaf@aepfle.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Olaf Hering , "K. Y. Srinivasan" , Haiyang Zhang , "Martin K. Petersen" Cc: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org On Thu, 2016-06-09 at 18:25 +0200, Olaf Hering wrote: > Reducing the sg_tablesize allows booting of 32bit kernels in VMs, > after > commit be0cf6ca301c61458dc4aa1a37acf4f58d2ed3d6 ("scsi: storvsc: Set > the > tablesize based on the information given by the host") > > [ 5.567138] hv_storvsc vmbus_1: adjusting sg_tablesize 0x800 -> > 0x20 Are you really sure 32 is the correct size? That caps transfers at 128 k. Even in the dim, dark, pre-64bit (at least on x86) days, our static limit for sg tablesize was 128 (0.5M). I know 32 it what it had before, but the reason for the commit you quote was to improve performance ... James