From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 14 Nov 2016 10:05:03 -0800 From: Christoph Hellwig To: Jens Axboe Cc: Christoph Hellwig , axboe@kernel.dk, linux-block@vger.kernel.org Subject: Re: [PATCHSET] Add support for simplified async direct-io Message-ID: <20161114180503.GA31126@infradead.org> References: <1479144519-15738-1-git-send-email-axboe@fb.com> <20161114173728.GA22167@infradead.org> <71ce9ae3-214d-b248-3507-cc96bea41a9b@fb.com> <20161114180052.GA24476@infradead.org> <4f30a528-9996-4c6a-9513-8aa2054e4d4b@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4f30a528-9996-4c6a-9513-8aa2054e4d4b@fb.com> List-ID: On Mon, Nov 14, 2016 at 11:02:47AM -0700, Jens Axboe wrote: > > We need it unless we want unbounded allocations for the biovec. With a > > 1GB I/O we're at a page size allocation, and with 64MB I/Os that aren't > > unheard of we'd be up to a 64 pages or an order 6 allocation which will > > take down the VM. We also need to pin down all the user memory while > > doing the I/O instead of having throttling on the bio mempool before > > doing the get_user_pages. > > Just add the iterator and loop for every X pages? We can even put a plug > around it, if we have to. That's pretty much what my patch does..