From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F435C3A589 for ; Tue, 20 Aug 2019 17:13:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF8F4214DA for ; Tue, 20 Aug 2019 17:13:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729820AbfHTRNc (ORCPT ); Tue, 20 Aug 2019 13:13:32 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:36512 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725971AbfHTRNb (ORCPT ); Tue, 20 Aug 2019 13:13:31 -0400 Received: (qmail 5200 invoked by uid 2102); 20 Aug 2019 13:13:30 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 20 Aug 2019 13:13:30 -0400 Date: Tue, 20 Aug 2019 13:13:30 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Andrea Vai cc: Johannes Thumshirn , Jens Axboe , , , Himanshu Madhani , Hannes Reinecke , Ming Lei , Omar Sandoval , "Martin K. Petersen" , Greg KH Subject: Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6 In-Reply-To: <307581a490b610c3025ee80f79a465a89d68ed19.camel@unipv.it> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Mon, 19 Aug 2019, Andrea Vai wrote: > Hi Alan, > I attach the two traces, collected as follows: > > - start the trace; > - wait 10 seconds; > - plug the drive; > - wait 5 seconds; > - mount the drive; > - wait 5 seconds; > - copy a 500 byte file; > - wait 5 seconds; > - unmount the drive; > - wait 5 seconds; > - stop the trace. Still no noticeable differences between the two traces. They both include a 1.2 second delay shortly after the writing starts, and the initialization sequences are the same. I really don't know where to look for this. The only thing I can think of at this point is to repeat this test, but using a file large enough for the difference in writing speed to show up plainly. By the way, it would be best to run the tests with the smallest possible number of other USB devices plugged in. None at all, if you can arrange it. Alan Stern