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 CF97EC432C0 for ; Wed, 27 Nov 2019 21:50:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B00112154A for ; Wed, 27 Nov 2019 21:50:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727501AbfK0VuA (ORCPT ); Wed, 27 Nov 2019 16:50:00 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:49304 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727194AbfK0Vt7 (ORCPT ); Wed, 27 Nov 2019 16:49:59 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id 7D0BD22B48; Wed, 27 Nov 2019 16:49:55 -0500 (EST) Date: Thu, 28 Nov 2019 08:49:53 +1100 (AEDT) From: Finn Thain To: "Schmid, Carsten" cc: Andrea Vai , Ming Lei , Damien Le Moal , Alan Stern , Jens Axboe , Johannes Thumshirn , USB list , SCSI development list , Himanshu Madhani , Hannes Reinecke , Omar Sandoval , "Martin K. Petersen" , Greg KH , Hans Holmberg , Kernel development list Subject: Re: AW: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6 In-Reply-To: Message-ID: References: <20191109222828.GA30568@ming.t460p> <20191123072726.GC25356@ming.t460p> <20191125035437.GA3806@ming.t460p> <20191125102928.GA20489@ming.t460p> <20191125151535.GA8044@ming.t460p> <0876e232feace900735ac90d27136288b54dafe1.camel@unipv.it> <20191126023253.GA24501@ming.t460p> <0598fe2754bf0717d81f7e72d3e9b3230c608cc6.camel@unipv.it> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Wed, 27 Nov 2019, Schmid, Carsten wrote: > > > > The sheer volume of testing (probably some terabytes by now) would > > exercise the wear leveling algorithm in the FTL. > > > But with "old kernel" the copy operation still is "fast", as far as i > understood. If FTL (e.g. wear leveling) would slow down, we would see > that also in the old kernel, right? > > Andrea, can you confirm that the same device used with the old fast > kernel is still fast today? You seem to be saying we should optimize the kernel for a pathological use-case merely because it used to be fast before the blk-mq conversion. That makes no sense to me. I suppose you have information that I don't. I assume that your employer (and the other corporations involved in this) have plenty of regression test results from a variety of flash hardware to show that the regression is real and the device is not pathological. I'm not privy to any of that information so I will shut up and leave you guys to it. -- > > This in itself seems unlikely to improve performance significantly. > > But if the flash memory came from a bad batch, perhaps it would have > > that effect. > > > > To find out, someone may need to source another (genuine) Kingston > > DataTraveller device. > >