From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752868AbbBKND2 (ORCPT ); Wed, 11 Feb 2015 08:03:28 -0500 Received: from mx1.HRZ.tu-dortmund.de ([129.217.128.51]:38009 "EHLO unimail.uni-dortmund.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752240AbbBKND0 (ORCPT ); Wed, 11 Feb 2015 08:03:26 -0500 Date: Wed, 11 Feb 2015 14:02:37 +0100 From: Andrej Gelenberg To: Douglas Gilbert Cc: JBottomley@parallels.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, hch@lst.de, martin.petersen@oracle.com, elliott@hp.com Subject: Re: CONFIG_SCSI_MQ_DEFAULT cause slow direct write speed to usb stick Message-ID: <20150211140237.29101167@bigpc> In-Reply-To: <54DA81CA.2030303@interlog.com> References: <20150210195036.3dce0e9e@bigpc> <54DA81CA.2030303@interlog.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, my problem was, that write speed to the device is got really slow from 7 Mb/s to 250 Kb/s, so 16.76 Mb/sec is probably the speed limitation of the uSD Card or is close to that. Do you activated blk-mq for scsi in kernel config or in boot parameters? Regards, Andrej On Tue, 10 Feb 2015 17:10:18 -0500 Douglas Gilbert wrote: > Here is an example: > > # ddpt if=/dev/sg1 bs=512 of=x.bin > 1953792+0 records in > 1953792+0 records out > 1281 retries after EAGAIN error(s) during IO > time to transfer data: 59.678788 secs at 16.76 MB/sec > > That is not a bad transfer time but other utilities > or drivers might dwell longer on those (nuisance) EAGAINs.