From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [LSF/MM TOPIC NOTES] x86 ZONE_DMA love Date: Thu, 3 May 2018 05:13:22 -0700 Message-ID: <20180503121322.GA14864@infradead.org> References: <20180426215406.GB27853@wotan.suse.de> <20180427053556.GB11339@infradead.org> <20180427161456.GD27853@wotan.suse.de> <20180428084221.GD31684@infradead.org> <20180428185514.GW27853@wotan.suse.de> <20180503120338.GG4535@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Matthew Wilcox , "Luis R. Rodriguez" , Christoph Hellwig , Dan Carpenter , Julia Lawall , linux-mm@kvack.org, cl@linux.com, Jan Kara , matthew@wil.cx, x86@kernel.org, luto@amacapital.net, martin.petersen@oracle.com, jthumshirn@suse.de, broonie@kernel.org, Juergen Gross , linux-spi@vger.kernel.org, Joerg Roedel , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, "lsf-pc@lists.linux-foundation.org" To: Michal Hocko Return-path: Content-Disposition: inline In-Reply-To: <20180503120338.GG4535@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On Thu, May 03, 2018 at 02:03:38PM +0200, Michal Hocko wrote: > On Sat 28-04-18 19:10:47, Matthew Wilcox wrote: > > Another way we could approach this is to get rid of ZONE_DMA. Make GFP_DMA > > a flag which doesn't map to a zone. Rather, it redirects to a separate > > allocator. At boot, we hand all memory under 16MB to the DMA allocator. The > > DMA allocator can have a shrinker which just hands back all the memory once > > we're under memory pressure (if it's never had an allocation). > > Yeah, that was exactly the plan with the CMA allocator... We wouldn't > need the shrinker because who cares about 16MB which is not usable > anyway. The CMA pool sounds fine. But please kill GFP_DMA off first / at the same time. 95% of the users are either completely bogus or should be using the DMA API, and the few other can use the new allocator directly.