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[107.191.0.158]) by smtp.gmail.com with ESMTPSA id o138-v6sm880568ito.36.2018.07.02.14.41.49 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Jul 2018 14:41:51 -0700 (PDT) Subject: Re: [PATCH 00/14][V5] Introduce io.latency io controller for cgroups To: Andrew Morton , Josef Bacik Cc: kernel-team@fb.com, linux-block@vger.kernel.org, hannes@cmpxchg.org, tj@kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20180629192542.26649-1-josef@toxicpanda.com> <20180702142639.752759da566fd9074cf8edfe@linux-foundation.org> From: Jens Axboe Message-ID: <08f3bef3-7189-a368-74d9-b4c5e0edc824@kernel.dk> Date: Mon, 2 Jul 2018 15:41:48 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180702142639.752759da566fd9074cf8edfe@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/2/18 3:26 PM, Andrew Morton wrote: > On Fri, 29 Jun 2018 15:25:28 -0400 Josef Bacik wrote: > >> This series adds a latency based io controller for cgroups. It is based on the >> same concept as the writeback throttling code, which is watching the overall >> total latency of IO's in a given window and then adjusting the queue depth of >> the group accordingly. This is meant to be a workload protection controller, so >> whoever has the lowest latency target gets the preferential treatment with no >> thought to fairness or proportionality. It is meant to be work conserving, so >> as long as nobody is missing their latency targets the disk is fair game. >> >> We have been testing this in production for several months now to get the >> behavior right and we are finally at the point that it is working well in all of >> our test cases. With this patch we protect our main workload (the web server) >> and isolate out the system services (chef/yum/etc). This works well in the >> normal case, smoothing out weird request per second (RPS) dips that we would see >> when one of the system services would run and compete for IO resources. This >> also works incredibly well in the runaway task case. >> >> The runaway task usecase is where we have some task that slowly eats up all of >> the memory on the system (think a memory leak). Previously this sort of >> workload would push the box into a swapping/oom death spiral that was only >> recovered by rebooting the box. With this patchset and proper configuration of >> the memory.low and io.latency controllers we're able to survive this test with a >> at most 20% dip in RPS. > > Is this purely useful for spinning disks, or is there some > applicability to SSDs and perhaps other storage devices? Some > discussion on this topic would be useful. > > Patches 5, 7 & 14 look fine to me - go wild. #14 could do with a > couple of why-we're-doing-this comments, but I say that about > everything ;) I want to queue this up for 4.19 shortly - is the above an acked-by? Andrewed-by? Which do you prefer? :-) -- Jens Axboe