From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id B630D6B0292 for ; Mon, 14 Aug 2017 04:50:46 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id u199so124767060pgb.13 for ; Mon, 14 Aug 2017 01:50:46 -0700 (PDT) Received: from lgeamrelo12.lge.com (LGEAMRELO12.lge.com. [156.147.23.52]) by mx.google.com with ESMTP id h1si4277121pld.809.2017.08.14.01.50.45 for ; Mon, 14 Aug 2017 01:50:45 -0700 (PDT) Date: Mon, 14 Aug 2017 17:50:42 +0900 From: Minchan Kim Subject: Re: [PATCH v1 2/6] fs: use on-stack-bio if backing device has BDI_CAP_SYNC capability Message-ID: <20170814085042.GG26913@bbox> References: <1502175024-28338-3-git-send-email-minchan@kernel.org> <20170808124959.GB31390@bombadil.infradead.org> <20170808132904.GC31390@bombadil.infradead.org> <20170809015113.GB32338@bbox> <20170809023122.GF31390@bombadil.infradead.org> <20170809024150.GA32471@bbox> <20170810030433.GG31390@bombadil.infradead.org> <20170811104615.GA14397@lst.de> <20c5b30a-b787-1f46-f997-7542a87033f8@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20c5b30a-b787-1f46-f997-7542a87033f8@kernel.dk> Sender: owner-linux-mm@kvack.org List-ID: To: Jens Axboe Cc: Christoph Hellwig , Dan Williams , Matthew Wilcox , Andrew Morton , Linux Kernel Mailing List , linux-mm , Ross Zwisler , "karam . lee" , seungho1.park@lge.com, Dave Chinner , Jan Kara , Vishal Verma , "linux-nvdimm@lists.01.org" , kernel-team Hi Jens, On Fri, Aug 11, 2017 at 08:26:59AM -0600, Jens Axboe wrote: > On 08/11/2017 04:46 AM, Christoph Hellwig wrote: > > On Wed, Aug 09, 2017 at 08:06:24PM -0700, Dan Williams wrote: > >> I like it, but do you think we should switch to sbvec[] to > >> preclude pathological cases where nr_pages is large? > > > > Yes, please. > > > > Then I'd like to see that the on-stack bio even matters for > > mpage_readpage / mpage_writepage. Compared to all the buffer head > > overhead the bio allocation should not actually matter in practice. > > I'm skeptical for that path, too. I also wonder how far we could go > with just doing a per-cpu bio recycling facility, to reduce the cost > of having to allocate a bio. The on-stack bio parts are fine for > simple use case, where simple means that the patch just special > cases the allocation, and doesn't have to change much else. > > I had a patch for bio recycling and batched freeing a year or two > ago, I'll see if I can find and resurrect it. So, you want to go with per-cpu bio recycling approach to remove rw_page? So, do you want me to hold this patchset? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org