From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-f52.google.com ([209.85.210.52]:36040 "EHLO mail-ot1-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726501AbgAOPu5 (ORCPT ); Wed, 15 Jan 2020 10:50:57 -0500 Received: by mail-ot1-f52.google.com with SMTP id m2so11652008otq.3 for ; Wed, 15 Jan 2020 07:50:57 -0800 (PST) MIME-Version: 1.0 From: Mauricio Tavares Date: Wed, 15 Jan 2020 10:50:46 -0500 Message-ID: Subject: CPUs, threads, and speed Content-Type: text/plain; charset="UTF-8" Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: fio@vger.kernel.org Let's say I have a config file to preload drive that looks like this (stolen from https://github.com/intel/fiovisualizer/blob/master/Workloads/Precondition/fill_4KRandom_NVMe.ini) [global] name=4k random write 4 ios in the queue in 32 queues filename=/dev/nvme0n1 ioengine=libaio direct=1 bs=4k rw=randwrite iodepth=4 numjobs=32 buffered=0 size=100% loops=2 randrepeat=0 norandommap refill_buffers [job1] That is taking a ton of time, like days to go. Is there anything I can do to speed it up? For instance, what is the default value for cpus_allowed (or cpumask)[2]? Is it all CPUs? If not what would I gain by throwing more cpus at the problem? I also read[2] by default fio uses fork. What would I get by going to threads? [2] https://fio.readthedocs.io/en/latest/fio_doc.html#threads-processes-and-job-synchronization