From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: Why BFQ scheduler available only for NVMe device? To: Mikhail Gavrilov , linux-block@vger.kernel.org References: From: Jens Axboe Message-ID: <29ab009a-ca9d-13ea-4a87-afd641e489dd@kernel.dk> Date: Thu, 4 Oct 2018 10:26:07 -0600 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 List-ID: On 10/4/18 10:15 AM, Mikhail Gavrilov wrote: > Sorry I don't finded answer on my question. > Why BFQ scheduler available only for NVMe device? > > $ find /sys -name scheduler -exec grep . {} + > find: ‘/sys/kernel/debug’: Permission denied > find: ‘/sys/fs/pstore’: Permission denied > find: ‘/sys/fs/bpf’: Permission denied > /sys/devices/pci0000:00/0000:00:01.3/0000:02:00.1/ata5/host4/target4:0:0/4:0:0:0/block/sda/queue/scheduler:noop > deadline [cfq] > /sys/devices/pci0000:00/0000:00:01.1/0000:01:00.0/nvme/nvme0/nvme0n1/queue/scheduler:[none] > mq-deadline bfq > /sys/devices/pci0000:00/0000:00:07.1/0000:0c:00.3/usb4/4-3/4-3.4/4-3.4.1/4-3.4.1:1.0/host9/target9:0:0/9:0:0:0/block/sdb/queue/scheduler:noop > deadline [cfq] It isn't, but it's only available for MQ devices. For SCSI, you want to set: CONFIG_SCSI_MQ_DEFAULT=y and if that isn't feasible due to running a distro build, then you want to add scsi_mod.use_blk_mq=1 to your boot parameters. -- Jens Axboe