From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Garry Subject: Re: [PATCH] scsi: default to scsi-mq Date: Tue, 11 Jul 2017 11:22:38 +0100 Message-ID: References: <20170616082755.22832-1-hch@lst.de> <1499701840.3555.7.camel@wdc.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from szxga02-in.huawei.com ([45.249.212.188]:9819 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753081AbdGKKW4 (ORCPT ); Tue, 11 Jul 2017 06:22:56 -0400 In-Reply-To: <1499701840.3555.7.camel@wdc.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Bart Van Assche , "hch@lst.de" , "linux-scsi@vger.kernel.org" , Linuxarm On 10/07/2017 16:50, Bart Van Assche wrote: > On Fri, 2017-06-16 at 10:27 +0200, Christoph Hellwig wrote: >> Remove the SCSI_MQ_DEFAULT config option and default to the blk-mq I/O >> path now that we had plenty of testing, and have I/O schedulers for >> blk-mq. The module option to disable the blk-mq path is kept around >> for now. >> >> Signed-off-by: Christoph Hellwig >> --- >> drivers/scsi/Kconfig | 11 ----------- >> drivers/scsi/scsi.c | 4 ---- >> 2 files changed, 15 deletions(-) >> >> diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig >> index 3c52867dfe28..d384f4f86c26 100644 >> --- a/drivers/scsi/Kconfig >> +++ b/drivers/scsi/Kconfig >> @@ -47,17 +47,6 @@ config SCSI_NETLINK >> default n >> depends on NET >> >> -config SCSI_MQ_DEFAULT >> - bool "SCSI: use blk-mq I/O path by default" >> - depends on SCSI >> - ---help--- >> - This option enables the new blk-mq based I/O path for SCSI >> - devices by default. With the option the scsi_mod.use_blk_mq >> - module/boot option defaults to Y, without it to N, but it can >> - still be overridden either way. >> - >> - If unsure say N. >> - >> config SCSI_PROC_FS >> bool "legacy /proc/scsi/ support" >> depends on SCSI && PROC_FS >> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c >> index 1bf274e3b2b6..3d38c6d463b8 100644 >> --- a/drivers/scsi/scsi.c >> +++ b/drivers/scsi/scsi.c >> @@ -800,11 +800,7 @@ MODULE_LICENSE("GPL"); >> module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR); >> MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels"); >> >> -#ifdef CONFIG_SCSI_MQ_DEFAULT >> bool scsi_use_blk_mq = true; >> -#else >> -bool scsi_use_blk_mq = false; >> -#endif >> module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO); >> >> static int __init init_scsi(void) > > Since a fix for the performance regression triggered by this patch will be upstream > soon (see also https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=32825c45ff8f4cce937ab85b030dc693ceb1aa0a): > FYI, on linux-next 20170711 (which now includes the above patch Bart mentioned) we see a large performance regression on hisi_sas (LLDD does not config shost for mq). fio read mode iops goes from ~833K (scsi_mod.use_blk_mq=n on cmdline) to ~320K John > Acked-by: Bart Van Assche > > > >