From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 5/6] f2fs: add a kernel thread to issue discard commands asynchronously Date: Mon, 16 Jan 2017 09:32:20 -0800 Message-ID: <20170116173220.GA2199@infradead.org> References: <20170112224407.54026-1-jaegeuk@kernel.org> <20170112224407.54026-5-jaegeuk@kernel.org> <20170113080159.GB31777@infradead.org> <20170113191211.GB1301@jaegeuk.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170113191211.GB1301@jaegeuk.local> Sender: linux-fsdevel-owner@vger.kernel.org To: Jaegeuk Kim Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, axboe@kernel.dk List-Id: linux-f2fs-devel.lists.sourceforge.net On Fri, Jan 13, 2017 at 11:12:11AM -0800, Jaegeuk Kim wrote: > Previously, I've done to issue discard bios asynchronously. But the problem that > I've got is that was not enough. When testing nvme SSD with noop IO scheduler, > submit_bio() was blocked at every 8 async discard bios, resulting in very slow > checkpoint process which blocks most of other FS operations. Where does it block? Are you running out of request? What driver is this on top of?