From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.18\)) Subject: Re: testing io.low limit for blk-throttle From: Paolo Valente In-Reply-To: <20180426183200.GK1911913@devbig577.frc2.facebook.com> Date: Thu, 3 May 2018 18:35:01 +0200 Cc: Joseph Qi , linux-block , Jens Axboe , Shaohua Li , Mark Brown , Linus Walleij , Ulf Hansson , LKML Message-Id: <11A022BD-AAE9-4508-A233-AE05DE33C60A@linaro.org> References: <4c6b86d9-1668-43c3-c159-e6e23ffb04b4@gmail.com> <18accc1e-c7b3-86a7-091b-1d4b631fcd4a@gmail.com> <536A1B1D-575F-4193-ADA6-BA832AEC7179@linaro.org> <20180426183200.GK1911913@devbig577.frc2.facebook.com> To: Tejun Heo List-ID: > Il giorno 26 apr 2018, alle ore 20:32, Tejun Heo ha = scritto: >=20 > Hello, >=20 > On Tue, Apr 24, 2018 at 02:12:51PM +0200, Paolo Valente wrote: >> +Tejun (I guess he might be interested in the results below) >=20 > Our experiments didn't work out too well either. At this point, it > isn't clear whether io.low will ever leave experimental state. We're > trying to find a working solution. >=20 Thanks for this update, Tejun. I'm still working (very slowly) on a survey of the current state of affairs in terms of bandwidth and latency guarantees in the block layer. The synthesis of the results I've collected so far is, more or less: "The problem of reaching a high throughput and, at the same time, guaranteeing bandwidth and latency is still unsolved, apart from simple cases, such as homogenous, constant workloads" I'm anticipating this, because I don't want to risk to underestimate anybody's work. So, if anyone has examples of how, e.g., to distribute I/O bandwidth as desired among heterogenous workloads (for instance, random vs sequential workloads) that might fluctuate over time, without losing total throughput, please tell me, and I'll test them. Thanks, Paolo > Thanks. >=20 > --=20 > tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751476AbeECQfH (ORCPT ); Thu, 3 May 2018 12:35:07 -0400 Received: from mail-wr0-f179.google.com ([209.85.128.179]:45455 "EHLO mail-wr0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751160AbeECQfE (ORCPT ); Thu, 3 May 2018 12:35:04 -0400 X-Google-Smtp-Source: AB8JxZoU4iWG+X3d42dWOEJnnsVyqEBMAOhrbpX/esROYr4Jc+3oOvf82DHK+wDdIlNVp79eej8C+A== Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.18\)) Subject: Re: testing io.low limit for blk-throttle From: Paolo Valente In-Reply-To: <20180426183200.GK1911913@devbig577.frc2.facebook.com> Date: Thu, 3 May 2018 18:35:01 +0200 Cc: Joseph Qi , linux-block , Jens Axboe , Shaohua Li , Mark Brown , Linus Walleij , Ulf Hansson , LKML Message-Id: <11A022BD-AAE9-4508-A233-AE05DE33C60A@linaro.org> References: <4c6b86d9-1668-43c3-c159-e6e23ffb04b4@gmail.com> <18accc1e-c7b3-86a7-091b-1d4b631fcd4a@gmail.com> <536A1B1D-575F-4193-ADA6-BA832AEC7179@linaro.org> <20180426183200.GK1911913@devbig577.frc2.facebook.com> To: Tejun Heo X-Mailer: Apple Mail (2.3445.6.18) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w43GZBkQ031170 > Il giorno 26 apr 2018, alle ore 20:32, Tejun Heo ha scritto: > > Hello, > > On Tue, Apr 24, 2018 at 02:12:51PM +0200, Paolo Valente wrote: >> +Tejun (I guess he might be interested in the results below) > > Our experiments didn't work out too well either. At this point, it > isn't clear whether io.low will ever leave experimental state. We're > trying to find a working solution. > Thanks for this update, Tejun. I'm still working (very slowly) on a survey of the current state of affairs in terms of bandwidth and latency guarantees in the block layer. The synthesis of the results I've collected so far is, more or less: "The problem of reaching a high throughput and, at the same time, guaranteeing bandwidth and latency is still unsolved, apart from simple cases, such as homogenous, constant workloads" I'm anticipating this, because I don't want to risk to underestimate anybody's work. So, if anyone has examples of how, e.g., to distribute I/O bandwidth as desired among heterogenous workloads (for instance, random vs sequential workloads) that might fluctuate over time, without losing total throughput, please tell me, and I'll test them. Thanks, Paolo > Thanks. > > -- > tejun